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This paper presents a methodology of designing an amplifier integrated with a microstrip filter using an active coupling matrix. The microstrip filter is directly coupled to the active device, and the integrated filter amplifier can achieve filtering as well as matching functionalities, simultaneously, eliminating the need for separate matching networks. The filter amplifier is represented by an active coupling matrix, with additional columns and rows in the matrix corresponding to the active transistor. The matrix can be used to calculate the S-parameter responses (i.e., the return loss and the gain) and the initial dimensions of the integrated device. Moreover, the integration of a filter and an amplifier leads to a reduced loss and a more compact architecture of the devices. An X-band microstrip filter amplifier has been designed and demonstrated as an example. Microstrip technology has been chosen because of its appealing advantages of easy fabrication, low cost, and most importantly, easy integration with active devices.

This paper presents an improved design of a rectangular microstrip antenna at 920 MHz by backing it with an appropriate cavity wall to enhance the isolation between the transmitter and receiver antenna for use in applications, where the weak received power gets masked by the direct coupled power between two antennas. Antennas having 0.12 λ cavity wall with separation gap of 0.36 λ resulted in an isolation of 52.6 dB at a resonance frequency of 920 MHz with maximum and minimum isolation of 71.4 dB and 49.1 dB, respectively for 5% BW of the antenna designed. These antennas were fabricated and tested, which are used in the development of Continuous Wave Ground Penetrating Radar with an online graphical user interface; leading to the validation of the usefulness of proposed antennas. The isolation achieved at an optimised separation of the antennas enabled detection of metal targets as small as a bunch of wire buried 20 cm in the soil and non-metal, like wood and plastic buried in soil. It enabled the detection of a circular steel target of radius 12.5 cm buried at a depth of 65 cm in loose semi-dry pebbled soil.

A technique employing the use of directly coupled stacked patches to increase impedance bandwidth with reduced cross-polarization is proposed in this paper. The top stacked multi-resonator configur...

The rural-isolated agricultural region in Iraq and some developing countries lack access to electricity, and thus the primarily alternative is to use diesel water pumping systems to irrigate their crops. However, due to a rise in the oil's price on the international market, toxic pollution from burning oil, high maintenance costs, and short lifespans have been challenged to create more viable alternatives. Renewable energy can limit the use of fossil fuels, particularly by using the solar-powered water pumping system. This article aimed at finding an optimal design for a direct-coupled photovoltaic water pumping system in Iraq. The article presents the significant design aspect for an optimal system, such as the groundwater aquifer depth, installation aspect, cost, and irrigation efficiency. The design offers a combination of sprinkler and environmentally sustainable and cost-effective photovoltaic technology to reduce electricity and water use. A deep well to the storage system is adopted with, 40m maximum well depth, 90m3 reservoir, 1200W submersible pump, and 1800 Wp, which can supply water to 12 greenhouses for three days. The yearly results show pumping efficiency is increased up to 42.6%, used water need is achieved at 10950 m3, and unused energy is reduced by 48.8%.

This work is believed to be the first report of a single-supply quasi-enhancement-mode GaN-based monolithic microwave integrated circuit (MMIC) amplifier that operates from dc to 50 GHz. The quasi-E-mode GaN high electron mobility transistors (HEMTs) have an f T of 120 GHz and a positive turnon voltage, Vgs-on, that enables an all positive-supply, regulated self-bias over threshold variation, and two-stage direct-coupled frequency response down to dc. Core to the quasi-E-mode design topology is a 237-GHz f T -multiplier transconductance gain stage to enhance the broad bandwidth response. The quasi-E-GaN MMIC obtains a gain of 11.4 dB at dc, 7 dB at 40 GHz, and 5.5 dB at 50 GHz. The 3-dB bandwidth is 31 GHz with return-losses

In some cases, current amplifiers have an advantage over voltage amplifiers. This is due to the fact that a significant part of the parasitic parameters of integrated circuits are capacitances. In this case, it is necessary to take into account the fact that, according to the laws of switching, the voltage across the capacitor cannot change abruptly, while the current through the capacitor can change abruptly. Thus, when designing electronic circuits for various analog-digital and digital-analog accessories and systems, one should be guided by the principle of current amplification. For this, it is advisable to use converters — current-current amplifiers (CCA). Functional and schematic diagrams of a current-to-current converter with a grounded load with variable transmission coefficients based on a push-pull DC amplifier, the complexity of which is less known, are considered. The linearity errors and zero bias currents of the PPDA are estimated depending on the value of the transmission coefficients of a particular. It showed that the linearity errors do not exceed 0,001 %, and the bias current does not exceed 0,5 μA. This makes it possible to use these devices in high-frequency electronic systems and devices. The optimal values of the tuning resistor are determined, at which the linearity errors at the given transmission ratios are minimal. The dynamic characteristics of the PPDA are analyzed using the frequency response, phase response and transient response for the given current transfer coefficients. It is proved that the bandwidth is as wide as possible and is determined by the limiting frequency of the transistor amplification.

A dual eighth-mode substrate integrated waveguide (EMSIW) cavity resonator-based circularly polarized (CP) antenna is proposed. The compact-sized antenna in this work is operated in dominant TE 101 mode operating at 3.6 GHz for 5G new radio (NR) use. The direct coupling between the EMSIW resonators, placed orthogonal to each other, provides right-hand CP (RHCP) radiation. The bandwidth (S 11 @-10dB) of the proposed antenna was found equal to 140 MHz with a 3-dB axial ratio (AR) bandwidth of 30 MHz, whereas the peak gain realized is 1.35 dBic. A new Figure-of-Merit (FoM) for performance comparisons is proposed. Its significantly high value for the proposed antenna is observed compared to the previously reported study, primarily due to its compact size.

In recent years the need for analog integrated circuits with low-voltage and low-power is more than urgent. The main reason for this need is the rapid growth of portable electronic devices for multimedia applications (laptops, netbooks, mobiles, etc.) and even more for biomedical devices applications. In many cases, these electronic devices provide connectivity to wireless networks (WLANs) and therefore they incorporate transceiver systems. Thus, requirements such as low-voltage and low-power are a necessity. One of the basic analog “building blocks” for circuit design is differential voltage amplifiers. This thesis presents complete solutions for low-voltage differential amplifiers in standard CMOS technology of 0.35μm and 0.18μm. The proposed amplifiers were designed with bulk-driven technique. In the first place are designed differential voltage amplifiers that include input stage with negative resistance circuitry. This way the proposed amplifiers improve the small input transconductance due to bulk-driven transistors. Thus, novel amplifier structures are obtained with a voltage supply equal even to 0.8V. The amplifiers performance is characterized both through simulation and experimental results. The convergence of simulation and experimental results demonstrate that the proposed amplifiers circuits designed with bulk-driven technique are significant solution in the design of low-voltage amplifiers. In the next step a differential bulk-driven voltage follower is designed with 1V voltage supply. The proposed follower is used as a differential input stage for a differential voltage amplifier with the same voltage supply. The proposed amplifier is capable to operate rail-to-rail for common mode input signals. Also, the proposed voltage follower is modified in order to operate in extreme voltage supply of 0.5V. The modified voltage follower is used, again, as a differential input stage for a differential voltage amplifier while the whole amplifier used a voltage supply equal to 0.5V. Both proposed amplifiers topologies that use bulk-driven differential voltage followers as input stages are complete solutions for low-voltage and ultra low-voltage amplifiers applications. Finally, a new technique for linear transconductance variation, applicable in any kind of transconductor, is introduced. The proposed technique is used to build a bulk-driven variable gain amplifier (VGA). The proposed VGA operate with 0.8V voltage supply while produce a gain range variation equal to 17dB. The amplifier could incorporate in an automatic gain control loop (AGC) for low-voltage applications. For this purpose, two bulk-driven voltage squarers circuits with voltage supply 0.8V and 0.5V was also proposed.

A broadband air-suspended stacked circular microstrip antenna is designed by employing a symmetrically direct coupled feed mechanism. The technique improves the bandwidth from 16.5% (for electromagnetically coupled stacked circular microstrip antenna) to 25.2% with a significant reduction in cross polarization components. The antenna results in a low cost solution and can be used for high power applications.

Propagation delay arises in a coupling channel due to the finite propagation speed of signals and the dispersive nature of the channel. In this paper, we study the effects of propagation delay that appears in the indirect coupling path of direct (diffusive)–indirect (environmental) coupled oscillators. In sharp contrast to the direct coupled oscillators where propagation delay induces amplitude death, we show that in the case of direct–indirect coupling, even a small propagation delay is conducive to an oscillatory behavior. It is well known that simultaneous application of direct and indirect coupling is the general mechanism for amplitude death. However, here we show that the presence of propagation delay hinders the death state and helps the revival of oscillation. We demonstrate our results by considering chaotic time-delayed oscillators and FitzHugh–Nagumo oscillators. We use linear stability analysis to derive the explicit conditions for the onset of oscillation from the death state. We also verify the robustness of our results in an electronic hardware level experiment. Our study reveals that the effect of time delay on the dynamics of coupled oscillators is coupling function dependent and, therefore, highly non-trivial.

An attempt is made to improve the impedance bandwidth (S11) of a microstrip antenna by means of the gap-coupling method, yielding a bandwidth of 97.88% for the gap-coupled rectangular microstrip antenna (GC-RMSA) compared with 7.67% for the direct-coupled rectangular microstrip antenna with all dimensions the same. The maximum gain of the proposed (GC-RMSA) design is 6.725 dB with antenna efficiency of 99.86%. The proposed antenna design is analyzed using the IE3D simulator. The microstrip line feed technique is used to energize the antenna, and its performance as a function of the gap between the elements (g) and the width of the feed strip (W) is investigated. The results show that the impedance bandwidth of the gap-coupled antenna depends on the coupling gap between the elements; indeed, as the gap (g) is increased up to a certain level, the bandwidth of the proposed antenna increases, resulting in a wideband characteristic. However, after a certain value of the gap (g), the bandwidth decreases due to spurious radiation, and the antenna characteristic changes from wide to dual band with a corresponding decrease in the bandwidth. The proposed antenna design covers the frequency range from 2.093 to 6.105 GHz, including the C-band, S-band uplink and downlink frequencies, Wi-Fi, Bluetooth, WLAN, and IEEE (a/b/g) standard applications.

In this paper, for the first time, modeling of a photovoltaic solar pump system integrated with a drip irrigation system is presented. There is some complexity in the adaption of the operating poin...

For the first time worldwide, the PEM electrolyzer directly coupled with the up-to-20 kW PV panels to produce hydrogen is reported as a demonstration of a high solar-to-hydrogen (STH) efficiency CO2-free hydrogen-production system. With the direct-coupling configuration, the power loss on an interlink DC/DC converter and its cost are avoided as known. Since the maximum power point (MPP) of PV unit is fluctuated by the fluctuating irradiance, this MPP is tracked by changing the number of the electrolyzer cell controlled by the MPPT algorithm, which allows changing the PV operating voltage. In our system, the averaged PV efficiency is 17.2%, and the electrolysis efficiency is 86.5% in a whole-day test. Thus, the STH efficiency is 14.9%. The hydrogen generation capacity of 18.6 N m 3 (5.01 kg CO2 reduction) is demonstrated in that whole-day test. Besides, the method to make the simulation model of the system from on-site data is shown. As a result, neither the preliminary test nor off-site test is needed. Therefore, this method can be used to check the condition of the entire system and each component in long-term operation which has never been found in the literature. The simulated model can also be used to investigate the PV-electrolyzer system.

Introduction. In modern experimental technology, the direction associated with the development of information-measuring systems for recording, pre-processing and analyzing excess low-frequency noise (flicker noise) is well known. Currently, such measuring systems are mainly presented in the form of particular solutions, due to the large variety of research goals and objectives. At the same time, for automation of the experiment, multichannel measuring complexes with the possibility of flexible reconfiguration of the measuring channel according to the task are highly demanded. It is obvious that any distributed measuring channel is represented as a multi-stage scheme with given functions and parameters of each stage, which makes it difficult for the measuring system to adapt to different conditions and tasks of the experiment. The logical solution to this problem is a deep unification of all components of the measuring channel while maintaining good performance characteristics. One of the main problems with this is the evaluation of the intrinsic noise of electronic elements, which provide for changing the parameters of the amplifier.Objective. Experimental analysis of the intrinsic noise of electronic potentiometers, development of the concept and study of parameters of a low-noise DC amplifier with a high degree of unification, the possibility of external electronic control and the use of built-in characteristics correction algorithms.Materials and methods. To achieve the set result, a method for measuring the noise of electronic potentiometers was proposed and experimental studies were carried out.Results. According to the calculation results and experimental studies, it was shown that the specific noise of the electronic potentiometers corresponds to the noise of the metal-film resistors, which makes it possible to use them in low-noise amplification stages. The developed circuit solutions allow the implementation of a unified amplifying module with cascading to build low-noise measuring DC paths based on electronic potentiometers. External and internal digital control allows you to significantly improve the performance of the measuring path as a whole and allows you to adapt it to a wide range of tasks.Conclusion. As part of the study, a method was proposed for measuring the noise of electronic potentiometers, analytical and experimental studies were carried out, and a prototype of a low-noise amplifier was developed and investigated.

The step-edge type high temperature superconductor (HTS) radio frequency (rf) superconducting quantum interference devices (SQUIDs) were fabricated from YBa2Cu3O7−δ thin films with a field sensitivity of 66 fT/Hz1/2. Even though the sensitivity of the rf SQUID sensor used in the experiments was degraded to 77 fT/Hz1/2 in the magnetic shielded room (MSR), the performance of the rf SQUID sensor was good enough for the ultra-low field (ULF) nuclear magnetic resonance (NMR) experiments at a measurement field of 61.5 μT. With the help of a strictly controlled fast switching circuit and a coupled LC circuit which acted as flux transformer, the signal-to-noise ratio (SNR) of the rf SQUID-based ULF NMR system with different operating points was measured. The optimum SNR was 40 dB which increased significantly by coupling an input coil closely beneath the rf SQUID sensor. The extracted 1/T1 value for pure water sample at 23 ∘C showed the rf SQUID based ULF NMR was an effective system for ULF NMR researches. All above, the direct coupled method and the control circuit show a great potential in the future rf SQUID-based ULF NMR &MRI system.

Currently, the share of combined-cycle power plants (CCPP) in the total installed power of Russia has increased due to their advantages over conventional power plants. Therefore, it is necessary to have a clear idea of how CCPPs operate in different modes. Most of the CCPPs installed in Russia were produced by foreign companies, which increases the uncertainty of data on the operation of CCPPs. Modeling of CCPPs and their operational features at large frequency excursions are discussed. Low-frequency events are considered in detail. If the compressor and the turbine are direct coupled, a frequency decrease leads to a lower compressor speed and, consequently, to reduced air supply to the combustion chamber. As a result, the air/fuel ratio is distorted, which can cause an increase in the gas temperature. To recover the temperature, the temperature controller signals to reduce the fuel supply. Thus, upon frequency decrease, the CCPP can start reducing power, which can lead to an increase in power deficit and an emergency. These processes are modeled mathematically. To prevent emergencies, an algorithm for power boosting during low frequency events is proposed. It is shown that this algorithm helps to increase the permissible power deficit, keeping the gas temperature within the permissible range.

In order to apply rotary atomizer to agricultural spraying system, the motor direct coupled rotary atomizer was proposed. The effect of operating conditions such as atomizing air flow rate, working fluid flow rate, and rotation speed of spinning cup on the atomization performance was investigated for the proposed direct coupled rotary atomizer. The motor speed was controlled in the range of 6,000 to 12,000 rpm using an alternating current transformer, and the atomizing air was supplied by the compressor. In this study, LDPA was used to analyze the spray characteristics of the rotary atomizer. The representative particle diameters of D10, SMD, MMD, D90, and DMax tended to decrease as the atomizing air flow rate and the motor speed increased, but increased as the working fluid flow rate increased. Also, SMD was found to be influenced by order of atomizing air flow rate> motor speed> working fluid flow rate, and DMax was influenced by order of operating fluid supply> motor speed> atomizing air flow rate.

In the designing of solar photovoltaic (PV) systems, which are directly coupled to batteries, it is of great importance to consider voltage-operating points of PV modules and batteries. Usually, batteries operating points are supposed to be near to the PV maximum power points to maximize the PV output. PV output voltage is affected by incident radiation, air temperature, shading, module orientation, PV technology; tilt angle and number of serial connected PV cells. This paper presents a PV model, which takes into account the number of PV cells connected in series, incident solar radiation and temperature as main factors affecting PV systems that are directly coupled to the batteries. The developed model was then validated by conducting some laboratory tests. In this study, an amorphous silicon thin film PV module was used. Electrical load data collected in Dodoma, Tanzania and lead acid battery with 24 V were also used in the designing and simulation of PV systems. Optimization and the laboratory test results have revealed how good the optimization tool is. The tool can select the optimal number of PV cells required for the given system. The selected optimal number of PV cells in series always matches with the battery operating voltage, which helps in the reduction of losses that usually occur in direct-coupled systems, hence maximizing PV output. The results presented in this paper are based on solar home system simulated in Dodoma, Tanzania; however, the model can be adapted to any other region and any type of PV module by changing input data like solar radiation, air temperature, longitude, latitude, load profile and STC parameters of the PV module respectively.

This paper presents a type of bandpass filter (BPF)-integrated single-pole double-throw (SPDT) switch using common shorted stepped-impedance resonator technique. The BPF-integrated ON-state with reverse-biased p-i-n diodes can be synthesized by classical coupled-resonator filter design theory, and the OFF-state with forward-biased p-i-n diodes is detuned which exhibits high OFF-state suppression (OSS). The transmission zeros due to the direct coupled feed, the cross-couplings and the cancelling effect of mixed electric and magnetic coupling are produced to improve the ON-state passband selectivity significantly. As examples, the third-order/fourth-order BPF-integrated SPDT switches at center frequency $f_{0} = 1$ GHz with ripple bandwidth of 110/100 MHz are designed, which show low insertion losses of 1.08/1.58 dB, sharp skirts, high roll-off rate of sidebands, high OSSs of 40.9/40.1 dB as well as high port-to-port isolation of 57.4/47.8 dB. Then, the switched 50- $\Omega $ matching circuits are in series with two output ports of above BPF-integrated SPDT switches, resulting in the absorptive OFF-state. The fabricated third-order/fourth-order BPF-integrated SPDT switches with absorptive OFF-state have the matched return losses of 30/28.2 dB, and their OSSs and port-to-port isolations are also improved.

Coupled resonators are commonly used in the design of filters with bandpass response. Majority of these filters are designed using edge coupled or direct coupled technique. This paper proposes the implementation of the edge coupled and the direct coupled technique in the designing of a bandpass filter using microstrip technology. This is to ease the bandwidth and the frequency control of the circuit. The bandpass filter is designed to operate at a centre frequency of 1.95 GHz, using the open-loop resonators for the ease of edge coupling and a λ/4 resonator for the direct coupling. The measured response of the prototyped design and the simulated response show good agreements between the two.

Conventionally, diplexers are designed by connecting two filters of different frequencies using a transmission T‐line junction which acts as a distribution network serving the individual filters. Here, a novel diplexer has been proposed and designed to utilize a directly coupled resonator as the distribution network. The directly coupled resonator is designed using two square open‐loop resonators of the same resonant frequency of 1.95 GHz. Coupling of the two resonators is achieved using a λ/4 transmission line to directly couple them. This process made the resonator pair to possess a dual‐mode resonator function, resonating at 1.85 and 2.05 GHz. Two bandpass filters are then designed in the corresponding modes of the resonator pair with 5% fractional bandwidth and coupled accordingly. This technique allowed the resonator pair to contribute to the resonant poles of the diplexer while functioning as the distribution network.

High power gyrotrons typically produce RF power in a ${HE}_{11}$ waveguide inside the vacuum. The direct coupler was Gaussian free-space mode. An internal converter transforms the integrated into the 110 GHz, 1 MW, short pulse gyrotron at MIT, whispering gallery mode from the cavity to a Gaussian beam using a shown in Fig. 1. Tests indicated that the gyrotron produced the quasi-optical launcher and a series of mirrors. Transmission of this same output power and efficiency as the conventional Gaussian power typically requires transformation into an ${HE}_{11}$ mode in corrugated waveguide. This conversion is achieved using a Mirror Optical Unit, which uses a second series of mirrors. The transformation of the whispering gallery mode to a Gaussian beam and then to an ${HE}_{11}$ mode requires a complexity of RF structures, increasing cost and RF losses. This program is developing a coupler that transforms the whispering gallery mode directly into an ${HE}_{11}$ mode inside the gyrotron. This results in significant reduction in gyrotron cost and RF losses and eliminates the Mirror Optical Unit.

This paper presents cascade amplifier with parametric variation using CMOS technology which can be stimulated at lower technology node. Amplifiers used for high frequency operations and higher bandwidth designed by BJT technology undergoes various limitations like small scale integration, power consumption and high frequency operation. CMOS Technology has an edge over BJT in various terms like low power dissipation, large-scale integration and high speed. This paper reflects the advantages of using MOSFET Technology for direct coupled common emitter followed by common base amplifier where we try to apply parametric variations in the proposed work which directly reduces the leakage current and hence power consumption in CMOS Technology. This research depicts trusted changes in power consumption for CMOS based cascade amplifier as compared to conventional cascade amplifier. The research paper also shows high performance by changing “w/l” ratio as a process parameter for a particular Technology node. In this paper, chip variations and environmental variation including FinFET Technology are taken into account with material properties to reduce the power consumption of cascade amplifier in the standby mode. The proposed work has several applications in high frequency amplifier design where parameters associated with amplifier can be improved by parametric variation and proposed FinFET based amplifier design.

Three fourth-order buck-boost converters with improved dynamic response are proposed. The improved dynamic response is achieved starting from the uncoupled inductors topologies and performing reverse coupling. This leads to the shift of the right half plane (RHP) zeros to the left half plane (LHP). The state-space small signal model is developed and the control-to-output transfer functions are derived. A comparison is made to the uncoupled and direct coupled topologies revealing the RHP zeros elimination. The simulations confirm that also with reverse coupling the input and output currents still maintain their smooth nature.

The offset voltage (V off ) of the BJT and CMOS two-stage operational amplifiers (Op-Amps) substantially depends on the numerical values (differences from unit) from the current ratio (K i ≈1) of the current mirrors (CM). The CM parameter is also influenced by the Early voltage of their dominant active components. For the JFET technologies (Si, SiC, GaAs and others) with a low noise level, there are no high-quality CMs of this class today, or their construction (at K i =1) is associated with a significant deterioration of other parameters of the Op-Amp. Nowadays, the current JFET mirrors are the weakest link in modern JFET analog circuitry and it is impractical to use them in the structure of the JFET Op-Amps. For the first time the article poses and solves the problem of determining the conditions for exclusion of the CMs in the JFET Op-Amp for the case when it is necessary to obtain a small V off . It is shown that for this, three identical reference current sources should be used, which are implemented on the JFET transistors and the local negative feedback resistors. The V off of the Op-Amps with the classical and proposed architectures are compared. The computer simulation results of the offset voltage (V off ) in the LTspice environment are presented, which show that silicon JFet direct coupled Op-Amps without CM have a systematic component of V off at the level of tens to hundreds of microvolts and voltage gain of more than 80 dB in a wide temperature range.

The design and the fully coupled Thermodynamic and Structural Mechanics simulation of a Spatial Power Amplifier are described in this paper. The amplifier is realized in a WR90 waveguide, employing Fin-Line Transitions and Monolithic Microwave Integrated Circuit Solid State Power Amplifiers. Global performances of active devices and combining structure have a critical dependence to the thermo-mechanical condition of operation. The temperature alterations and thermal expansions, related to the power dissipation of the devices, have been analyzed in order to lead the amplifier at extreme power output, avoiding malfunctions. The proposed analysis accounts for the effects of different distributions of heat flux and stresses as a consequence of the different power consumption of the Driver and Final stage transistors. The amplifier combines 16 active devices of 7.9 W maximum power output with a power dissipation of 20 W, heating the transistor channel to140° and deforming the mechanical structure to 4.9µm with a maximum stress of 0.41 GN/m2. A maximum power output of 112W with a Return Loss greater than 12 dB in the whole X-Band is ensured

In the proposed work, 3–7 GHz two-stage Ultra-Wide-Band (UWB) power amplifier has been designed and simulated using UMC 0.18 μm CMOS technology. The proposed Power Amplifier (PA) design exhibits the simplest topology to fulfill the requirement of low gain ripple, good linearity, and small group delay variations all simultaneously for Ultra-Wide-Band (UWB) application and covering only 0.75 mm2 area of silicon. In order to obtain low gain ripple, good group delay variations and linearity at the same time, the inductive peaking and class-AB operation are employed at both the stages. The post-layout simulation results show lowest gain ripple of 19 ± 0.3 dB, good input and output matching (

The MOSFET (Metal Oxide Field Effect Transistor) is one of the most widely used semiconductor devices in analog and digital circuits for amplification and switching. It is a highly popular power de vice used in power electronics. The important advantages of MOSFET include higher efficiency at lower operating voltages; there is no gate current resulting in high input impedance enhancing its switching speeds. A differential amplifier is a direct coupled amplifier that amplifies the difference between the two input signals arriving at its input and suppresses the common voltage between the two inputs. The important parameter that determines the performance of a differential amplifier is its CMRR which determines the capability of it to amplify the differential mode signal and cancel the common mode signal i.e. noise. To improve the CMRR, the resistor R E is replaced by an active load i.e. the current mirror circuit. In this paper, the performance of MOSFET differential amplifier (BiMOS Differential pair) is evaluated using Active MOSFET Load, Wilson Current Mirror and Widlar Current Mirror Circuits. The results of the implementation show that the highest CMRR (31.48 dB) is obtained by using the Diode Connected Topology.

This paper presents a direct coupled open ended spiral resonator (OESR) on a microstrip line for band stop filter applications. Using the insertion loss method, a band stop of third order with Butterworth response is realized. Using Kuroda’s identity LC filter transformation to open and closed stubs is carried out. This filter is modified as a direct coupled open ended spiral resonator (OESR) for achieving same response. Design equations for OESR configuration is provided based on the analytical study using ANSYS HFSS. Design equations predict the resonance of the filter with less than 3 % error. Testing the resultant prototype provided results identical with simulations. A size reduction of 98.4 % is achieved for the OESR compared to standard filters realized using open/short circuited stub microstrip lines. Thus, a miniaturized version of a planar band stop filter is realized with a size of 0.33 λ 0 × 0.17 λ 0 for different communication gadgets.

A highly linear X-band low-noise amplifier (LNA) is proposed and implemented in a standard 0.18- $\mu \text{m}$ CMOS technology. The LNA features both high- and low-gain operation modes. In its normal high-gain mode, the LNA shows a small-signal gain of 13.6 dB with an IIP3 of +9.5 dBm and a noise figure of 4.7 dB. The two-stage amplifier draws 90 mA from the 3.3-V power supply to achieve +14.8 dBm output P1dB (+2.2 dBm input P1dB). In the low-gain mode, the gain is reduced by about 10 dB to further enhance the linearity and to accommodate very large blockers. Accordingly, the input P1dB is enhanced to +13.7 dBm while the noise figure is increased by 8.1 dB. A technique is also introduced to maintain the input matching when the LNA is switched to operate in the low-gain mode.

In this brief, a design technique for tapered distributed low-noise amplifiers (LNAs) is presented. A circuit model is developed for gain and noise analysis of a nonuniform distributed amplifier (DA). It is shown that by optimal tapering of gate and drain transmission lines and transistors, the tapered distributed LNA can provide lower broadband average noise figure (NF) compared to a uniform DA. A proof-of-concept integrated circuit is implemented using a 0.1- $\mu \text{m}$ GaAs pHEMT process. The amplifier provides average gain of 15.2 dB and 3-dB bandwidth of 43.3 GHz. The average NF of 2.3 dB and minimum NF of 2.0 dB are achieved over 2–40 GHz. The chip consumes 55 mA current from a 2-V supply.

In this paper, a current-mode Class-DE (CMCDE) power amplifier is presented. The CMCDE with linear shunt capacitance under zero-current switching (ZCS) and zero current-derivative switching (ZCDS) conditions at any active time is analyzed, simulated, and fabricated. An analytical theory along with the design simulation and verification by experimental results at active time $\tau _{d}= \pi / 2$ are given. It was shown that the peak switch voltage can be adjusted with active time $\tau _{d}$ . The proposed amplifier offers several desirable features, such as simple structure and possibility to include the parasitic inductance and shunt capacitance of the mosfet into a load network, so that ZCS condition is maintained. The results show that the switch voltage and current obtained in CMCDE amplifier are inversed in comparison to the voltage-mode Class-DE (VMCDE) amplifier by using a simple output matching network and series inductance. Also, we could control the harmonics in one resonator in comparison to multiple resonators used in some high-efficiency power amplifiers. The measured maximum drain efficiency of 88% and power gain of 22 dB at 42-dBm output power was obtained at 4 MHz for CMCDE amplifier at active time $\tau _{d}= \pi / 2$ .

The maintenance issue of batteries and the limited power level of energy harvesting is addressed by the presented integrated micropower supply. Connected to the 120/230- $\text {V}_{\text {RMS}}$ mains, it provides a 3.3-V ac output voltage, suitable for applications such as the Internet-of-Things and smart homes. The micropower supply consists of a fully integrated ac–dc and dc–dc converter with one external low-voltage surface mount device buffer capacitor, resulting in an extremely compact size. Fabricated in a low-cost 0.35- $\mu \text {m}~700$ -V complimentary metal-oxide-semiconductor technology, it covers a die size of 7.7 mm2. The ac–dc converter is a direct coupled, full-wave rectifier with a subsequent series regulator. The dc–dc stage is a fully integrated capacitive 4:1 converter with up to 17-V input and 47.4% peak efficiency. The power supply comprises several high-voltage control circuits including level shifters and various types of charge pumps (CPs). A source-supplied CP is utilized that supports a varying switching node potential. The overall losses are discussed and optimized, including flying capacitor bottom-plate losses. The power supply achieves an output power of 3 mW, resulting in a power density of 390 $\mu \text {W}/ \text {mm}^{2}$ . This exceeds prior art by a factor of 11.

Total bandwidth of existing wireless communication technologies covers a wide frequency range of over one octave. But most existing power amplifier configurations cannot meet this requirement while at the same time maintaining a high efficiency. Therefore, a new structure that can achieve multioctave bandwidth is proposed in this paper together with the design methodology. The difficulty in realizing a bandwidth larger than one octave lies in the overlapping of fundamental and harmonic frequencies. Regarding this problem, the continuous class-F mode is extended to allow a resistive second harmonic impedance, rather than the pure reactive one. With the relaxed design requirements and overlapping design space of fundamental and second harmonic frequencies, harmonic tuning and fundamental frequency matching networks can be designed separately. More importantly, broadband matching for fundamental frequencies can be implemented simply by considering only three fundamental frequency points using the multiple frequencies matching method. To verify the validity of the proposed methodology, a multioctave power amplifier was designed, fabricated, and measured. Measured results verify a wide bandwidth of 128.5% from 0.5 to 2.3 GHz. Over this frequency range, drain efficiency was larger than 60% with output power greater than 39.2 dBm and large signal gain larger than 11.7 dB.

A low-power low-noise chopper amplifier for biosensor applications is proposed. To tackle the inherent ripple artifacts, it employs a simple ripple reduction method using a bandpass amplifier. The chopper amplifier is a linear periodic time-varying system. The method of harmonic transfer matrix is used to derive the signal and the noise harmonic transfer functions, and the theoretical results are confirmed by simulation and measurement results. Fabricated in a 130-nm standard CMOS process, the proof-of-concept prototype occupies a chip area of 0.28 mm2 and consumes $3.3~\mu {\text{A}}$ from a 1.2-V supply. The input referred noise is only 43 nV/ $({\mathrm {Hz}})^{1/2}$ .

This brief presents a new low-power miniature instrumentation amplifier based on the operational floating current conveyor (OFCC). The OFCC is a general-purpose current mode device capable of realizing all functions as an operational amplifier. The proposed OFCC is designed and implemented in both TSMC low-power 90-nm and UMC high-speed 130-nm CMOS technology for use in low-voltage applications. A single supply of 0.4 V is used to reduce the power consumption. The design utilizes the energy-efficient subthreshold region. A self-cascode technique is used to enhance the tracking capability of the OFCC. Post-layout simulation and Monte Carlo analysis show promising results. The current mode instrumentation amplifier in 90 nm occupies 0.023 mm2 while consuming $11~ {\mu }\text{W}$ with 14 kHz gain-independent bandwidth and common mode rejection ratio (CMRR) of 76 dB. The 130-nm design exhibits input referred noise of $1.1~ {\mu }\text{V}_{\text{RMS}}$ for a bandwidth of 0.07–150 Hz while consuming $14~ {\mu }\text{W}$ and CMRR of 65 dB with 100-kHz bandwidth with chip area 0.021 mm $^{{2}}$ .

This paper presents a design strategy to enhance the bandwidth of three-stage Doherty power amplifier (DPA) with operation upto 12-dB back-off. Based on the proposed strategy, a broadband 48-W DPA is designed and implemented using packaged CREE GaN transistors. The measured drain efficiency of 50%–61.8% at 12-dB back-off and 51.9%–66.2% at 6-dB back-off is obtained over the frequency range of 600–900 MHz. Over this 300-MHz band, the drain efficiency is between 51.1% and 78% at saturation. This corresponds to 40% fractional bandwidth. The three-stage DPA is also linearized with a three carrier 15-MHz WCDMA signal with a PAPR of 10.6 dB at various frequencies within operating band and shows the output signal qualifies spectral mask specifications.

Classical DC current transformer, based on a linear amplifier as a compensating amplifier, is well known as a power inefficient device. If the linear amplifier is replaced with switching counterpart, significant power saving can be achieved. A natural choice for replacement can be found in a half-bridge class-D amplifier. However, the half-bridge class-D amplifier is prone to bus-pumping effect, and direct replacement cannot be performed in a straightforward manner. This study presents an analysis of power consumption issues and irregular behaviour for a DC current transformer, caused by the bus-pumping effect. For the case of DC current measurement, the main issues are explained, giving better insight into power consumption, and possible hazards to transformer circuitry. Presented analytical results are experimentally verified.

A V-band low-power signal-reuse low-noise amplifier (SRLNA) implemented in 90 nm complementary metal-oxide-semiconductor technology is presented. The proposed SRLNA uses zero- V T and signal-reuse wake-up technologies to improve wake-up sensitivity and reduce power consumption. The SRLNA can be activated or turned off automatically based on the amplitude of the radio-frequency signal power. Time delays of the zero- V T envelope detector and limiting amplifier are analysed in order to loose the constraint on the maximum data-rate. Moreover, the relationship between noise figure (NF), power gain ( S 21 ), input and output return losses ( S 11 and S 22 ) of the SRLNA are discussed in detail, with the quality factors Q nf , Q I , Q in , and Q L defined for NF, S 21 , S 11 , and S 22 parameters derivations. The proposed SRLNA consumes 25 and 12 mW at activate and sleep modes, respectively. The sensitivity of the proposed SRLNA can achieve about -50 dBm.

In this paper, an ultra-wideband (UWB) low-noise amplifier (LNA) with low noise-figure (NF) and high power gain (S 21 ) using 0.18-um CMOS technology is presented, which operates from 3 GHz up to 12 GHz. In the proposed amplifier, a combination of noise-canceling and current-reused technique is used to reduce noise and power consumption, while the gain and the linearity will be improved. The dominant noise source is canceled by the noise-canceling technique. In addition, good input impedance matching is achieved with using both the inductive source degeneration and resistive feedback techniques. The proposed LNA achieves high and flat S 21 of 19.24–20.24 dB and S 11 less than −10 dB for frequencies 3–12 GHz. Additionally, flat NF of 1.72–1.99 dB is achieved for the frequency range of 3–12 GHz. Furthermore, the IIP3 is −5.5 dBm, power consumptions at 1.8-V supply voltage is 23.23 mW and the core layout size is 857.06 µm×770.72 µm.

Quasi-optical (QO) filter design is commonly based on the direct coupled bandpass filter topology with distributed resonator elements. Conventionally, prototypes with symmetrical impedance inverters are employed during synthesis, and as a result, this leads to resonators with custom lengths across the filter. This can be impractical from a QO filter implementation perspective, since spacers of arbitrary thickness may not be readily available. In this paper, we propose a novel impedance inverter equivalent network, which allows the development of prototypes where transmission lines across the filter structure to have predefined fixed lengths. Based on this technique, we developed a fourth-order QO filter prototype that composed of 2-D periodic arrays with subwavelength features. Its performance is verified with free-space measurement, and the measured results show good agreement with both full-wave and circuit simulation. Thus, it is shown that the proposed impedance inverter circuit can simplify the implementation of QO filters of higher order.

This paper presents an intrinsically linear wideband polar digital power amplifier (DPA) operating in semi class-E/F2 mode. Without using any type of digital pre-distortion (DPD), the proposed architecture achieves high linearity by accurately controlling its AM–AM and AM–PM characteristic curves through nonlinear sizing , overdrive-voltage control , and multiphase RF clocking without compromising the achievable output power or efficiency. Measurement results of the fabricated prototype in 40-nm bulk CMOS show −46 and −40 dBc adjacent channel power ratio (ACPR) for 20- and 40-MHz orthogonal frequency-division multiplexing (OFDM) signals, respectively. The measured error vector magnitudes (EVM) are −36 dB and −33 dB, respectively. Measured results indicate a $P_{\mathrm{ SAT}}$ , peak drain efficiency (DE), and power-added efficiency (PAE) of 14.6 dBm, 44%, and 26%, respectively, using a 0.5-V supply for the output stage at 2.2 GHz.

This paper presents a dual-channel low-noise bio-signal amplifier for the low-power wireless body area network (WBAN) nodes. A dual-channel three-input current-reuse (DTCR) structure is proposed to optimize the noise performance of amplifier. The chopper-stabilized technique is employed to reduce 1/f noise and the offset voltage. Moreover, a high input impedance is achieved by using the pre-charge technique. In addition, a DC offset canceling loop is employed to suppress the electrode offset. The proposed amplifier is implemented in a standard 0.18 μm CMOS process with an active area of about 0.68 × 0.73 mm2. The experimental results demonstrate that an input referred noise of 1.12 μVrms has been achieved over a bandwidth from 0.35 Hz to 150 Hz. The total power consumption of each channel is about 1.44 μW at the supply voltage of 1.2 V. And the amplifier achieves an input impedance of about 200 MΩ, a CMRR of 111 dB at 50 Hz and a PSRR of 87.5 dB at 50 Hz.

This paper presents an octave-bandwidth load modulated balanced amplifier (LMBA) that operates directly on a single modulated RF input. The architecture is based on the recently proposed LMBA technique, in which a control signal applied at the output isolation port of a balanced amplifier is used to modulate the apparent load impedance of the two devices comprising the balanced amplifier. In our approach, the injected control signal is used both as an active match and to dynamically load modulate the main devices to provide efficiency enhancement at back-off, thus extending the dynamic range compared to the original LMBA formulation. In this paper, we introduce a phase-compensation technique through which the active matching and load modulation tracks the frequency-dependent optimal loading trajectory of a packaged device. The result is a load-modulation power amplifier architecture able to perform an active, modulated match over an octave bandwidth. The technique is demonstrated over 1.8–3.8 GHz using packaged devices and an off-the-shelf hybrid coupler. The proof-of-concept octave RF-input LMBA has a peak CW output power of 44 dBm, with power added efficiency (PAE) over the 1.8–3.8 GHz operating frequency range of 37%–59% at peak power and 29%–45% at 6-dB output backoff. The RF-input nature of this architecture enables straightforward measurement with modulated signals; a W-CDMA signal at 3.8 GHz with 9-dB (measured) peak to average power ratio is demonstrated with adjacent channel leakage ratio of −30 dBc and average PAE of 18% for a 31-dBm average output power (2-dB backoff).

A broadband and highly efficient class-G supply modulated power amplifier (PA) system with 120-MHz instantaneous modulation bandwidth operating in the 1.8-GHz band is presented in this paper. The core element is the fast class-G supply modulator which switches the supply voltage of the RF PA between three discrete levels with a minimum pulse duration of 2.5 ns. Two designs for the drain bias interface between PA and modulator are evaluated where the best results are achieved for an implementation based on a $\lambda $ /4-wavelength RF-choke. Measurement results are presented for a 120-MHz contiguous carrier aggregated signal using eleven subcarriers with modulation bandwidths ranging from 5 to 20 MHz for each subcarrier. In combination with digital predistortion, the system achieves 38.5% PAE with −40-dB EVM and −46-dB ACLR for the 120-MHz multicarrier signal with a peak-to-average power ratio of 10 dB at the PA output and 39-dBm average output power. The total efficiency enhancement achieved by the class-G modulation is 13% points.

This paper presents a 60-GHz power amplifier (PA) utilizing a novel technique to achieve high efficiency at high output power levels. The proposed topology provides the capability of dual-mode operation. The output power of a conventional class-A power amplifier will be combined with the power provided by an amplifier operating at a different class to achieve higher efficiency at higher output levels. An enhanced cascode stage is designed to boost the power gain provided by driver stages coupled to the power stage with transformer-coupled impedance matching networks. Fabricated in 65-nm CMOS process, the measured gain of the 0.32-mm2 power amplifier is 17.7 dB at 60 GHz with a wide 3-dB bandwidth of 12 GHz while consuming 378 mW from a 1.2-V supply. A maximum saturated output power of 16.8 dBm is measured with the 14.5% peak power added efficiency (PAE) at 60 GHz. The proposed PA achieved a measured maximum PAE of 17.2% at 18.1-dBm-saturated power operating in high-power mode by applying 1.4-V supply.