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This study introduces the design of a practical three-stage operational amplifier (op-amp) using nested Miller compensation, particularly for piezoelectric actuators. Driving a piezoelectric actuator represents a challenge in amplifier design due to its large capacitive nature. A stable piezo driver needs to be free of oscillations and phase lag. Direct feedback compensation using a conventional Miller capacitor is an effective method as long as the capacitance of the load is considerably close to the value of the Miller capacitor. However, using a large capacitor causes a decrease in the slew rate and gain bandwidth. To avoid this, our design focused on the utilization of nested Miller compensation technique. A prototype of the design working at 100V peak to peak voltage (Vpp) is implemented using commercial off-the-shelf (COTS) components. The measurements show the successful driving capability and step-response of the op-amp design. In the design, Widlar current source is also utilized for thermal stability and short circuit protection. According to simulation results, the proposed op-amp has a slew rate of 0.5 V/μs, an open loop gain of 90dB with 3MHz Gain Bandwidth Product (GBP) and phase margin of 77°, and a common mode rejection ratio (CMRR) of 62dB.

We propose an all-CMOS, supply independent, second-order temperature compensated, process invariant, 10.09 μA current reference circuit working on a 1.8 V power supply. The current reference is built using an adaptive regulated cascode configuration integrated with a Widlar current source. It is implemented in 180 nm UMC MPW RF process and consumes an area of 0.014 mm2. It has a very low line sensitivity of 0.52 %/V and a temperature coefficient of 9.94 ppm/°C over the automotive temperature range of −40°C to 125°C. The proposed current reference is used to build a high quality, power efficient stable ring oscillator circuit working at 377.9 MHz frequency to be used in IoT SoCs. The ring oscillator shows a variation of less than 1.1 % in frequency, with supply voltage over the range 1.5 V to 2 V. The invariance of frequency with supply voltage can be exploited to reduce the power consumption up to 36.93 % in the oscillator circuit.

Technological process evolution can be described using advanced MOS models, focusing a low-currents reference as an excellent demonstrator. Using Monte Carlo method in a circuit simulation program, this paper offers a new approach on the influence of MOSFET threshold voltage on a classic Widlar current source, as a parameter with great impact in circuit behavior prediction, using both classical models and short-channel models for simulations. Finally, a new optimization method for the sum of the two resistances in Widlar mirror, based on an original mathematical calculus is presented.

On the basis of the existing research results of high-voltage synthesis experiments, this paper uses Matlab/Simulink software to model and analyze the voltage source and current source circuit of the 400V/200kA low-voltage synthesis circuit. The results show that the recovery voltage value provided by the voltage source circuit has a vital impact on the equivalence of the synthesis test. On this basis, the expected transient recovery voltage value can be obtained by adjusting the charging capacitor, the discharging reactor and the frequency modulation parameters, which can provide a theoretical basis for the domestic low-voltage synthesis test while saving the experimental investment cost. At the same time, this paper uses PIC16F877a single-chip microcomputer to realize the optimized design of the overall test control system of the low-voltage synthesis loop, which can realize the automatic charging and discharging function of the capacitor, and when the capacitor is charged, the charging circuit can be disconnected by itself to reduce manual operation

One of the crucial components of each bioimpedance measuring device is a constant current source. Finite element numerical device simulation was used to analyze track to track capacitances and compared to measurements on developed PCB with soldering elements. Here, we present an analysis based on a modified circuit of a single constant current source. Finite element numerical system simulation was used to evaluate track to track capacitances and compared to measurements on built PCB without soldering elements. One of the most important components of the bioelectric impedance devices and Bio-Electrical Impedance Analyzer (BIA) is the current source circuit. There are many types of circuits, such as current source, enhanced current source, general impedance convertor, Wien bridge circuit, voltage pick-up amplifier. This paper presents the modules of bioimpedance creation of software.

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.

The article presents the analysis of metrological properties of a two-current-source supplied circuit. It includes such data as precise and simplified equations for two circuit output voltages in the function of relative resistance increments of sensors. Moreover, graphs showing nonlinearity coefficients of both output voltages for two resistance increments varying widely are presented. Graphs of transfer resistances, depending on relative increments of sensors resistance were also created. The article also contains a description of bridge-based circuit realization with the use of a computer and a data acquisition (DAQ) card. Laboratory measurement of the difference and sum of relative resistance increments of two resistance decade boxes were carried out indirectly with the use of the created measurement system. Measurement errors were calculated and included in the article, as well.

In this paper, a novel AC magnetic transmitter current source circuit is proposed for application of frequency domain electromagnetic method (FEM) prospecting. The proposed current source circuit is capable of generating high frequency and high constant amplitude currents, which are key technical problems for FEM. It is suitable for very wide frequencies. The main circuit of the proposed current source consists of a rising-edge enhancing unit, a constant current control unit, and a high voltage clamping unit. Large constant clamping voltage is applied during the rising edge and the falling edge of the alternating square current to obtain a high frequency and high linearity current source. On the current flat stage, the constant current unit provides the energy to the load to ensure the constant amplitude of the output current. Detailed operations of the proposed magnetic current source are given. Simulation and experimental results demonstrate that the proposed circuit achieves short reversal time, the linearity of the rising/falling edge, constant amplitude and low power loss. These are the desired characteristics of the ac square current source probing transmitter for the magnetic FEM applications.

Bipolar current sources with a stability better than 0.1% in the temperature range of -30 to +70 °C are demanded for driving voice coil motors applied in a new ultra-quiet satellite platform, but almost none of the existing designs satisfy the harsh requirements. This paper presents a possible solution, which is essentially a floating-load, bipolar current source circuit with a dual feedback path. The key circuit is a composite amplifier (co-amp) composed of a high precision amplifier for error correction and a high power amplifier for load driving. The first feedback path comprises a specially designed four-wire current-sense resistor for current-to-voltage conversion and a discrete instrumentation amplifier for amplifying the converted voltage and closing the loop. The second feedback path is a proposed compensation network for loop stability. Error budgets for evaluating current stability and choosing key components of the circuit are comprehensively studied based on a derived rigorous current equation. Loop-stability problems attributable to the inductive load and the high open-loop gain of the co-amp are analyzed, and the proposed dual feedback compensation method is verified by theory, simulation, and measurement. All these contributions are demonstrated by three implemented prototypes with an output of up to ±2 A. The measured results agree well with theoretical predictions. The best and the worst stability performances of the three prototypes at +2 and -2 A are, respectively, 394 and 986 ppm in the temperature range of -30 to +70 °C, which are close to the theoretical value of 776 ppm.

In this paper, we introduce the design, development and implementation of a parallel architecture impedance measurement system for electrical impedance tomography. The system achieves a balance between speed, cost and system size. A 16-electrodes parallel impedance measurement system is designed around a phantom tank. We use an AD9834-based direct digital synthesizer module and improved Howland voltage controlled current source circuit to generate a 50 kHz constant sinusoidal current with a peak-peak amplitude up to 1 mA. The root-mean- square (RMS) potential on all the adjacent pairs of electrodes is measured directly by the analog-to-digital converter of the STM32 microcontroller unit (MCU). In order to enhance the system operation speed, a multi-MCU architecture is proposed here. 16 MCUs are connected in parallel to measure the voltage of each electrode and execute the fast Fourier transform operation at the same time, which guarantees a data collection rate of over 30 frames/s. The 16 slave MCUs use the InterIntegrated Circuit bus to communicate with the master MCU. The RMS data is then executed to obtain the impedance based on the acquired data.

In recent years, with the rapid development of process technology and portable electronic products, many devices have become thin, light, and power-efficient, and it is relatively important to provide a stable clock frequency generator for the system. In this paper, we propose an automatic PVT calibrated ring oscillator. By automatically compensating for temperature variations in the current source circuit, digital control is used to switch the working blocks to compensate for process variations. In addition, voltage-controlled capacitors are used to ensure that the supply voltage variability is stable to frequency. Our simulation results use an on-chip calibrated oscillator implemented in TSMC 90nm 1P9M CMOS process.

Open-type current sensors have been commonly used for DC motor controller, AC variable controller and Uninterruptible Power Supply. Recently they have begun to be used more widely, as the growth of renewable energy and smart-grid in power system. Considering most of the open-type current sensors are imported, developing the core technology needed to produce open-type current sensors is required. This paper describes the development and test results of open-type current sensors. Design of C type magnetic core, selection and test of a Hall sensor, design of current source circuit and signal conditioning circuit are described. 100A class DIP(Dual In-line Package) type and SMD(Surface Mount Devide) type open-type current sensors was made and tested. Test results show that the developed open-type current sensor satisfies the accuracy requirement of 2% and linearity requirement of 2% at 100 A of DC and AC current of 60Hz. Temperature compensation was carried out by using a temperature compensation circuit with NTC(Negative Temperature Coefficient) thermistor and the effect of the temperature compensation are described.

This paper presents a temperature-compensated CMOS current reference with low line regulation current mirror. The circuit is based on a bandgap reference voltage that achieves the temperature compensation of resistor by the negative temperature coefficient (TC) of a high-resistance polysilicon (HR poly) resistor with the positive TC of an n-well resistor. The low line regulation current mirror is implemented by using a negative feedback connected operational amplifier. Prototypes of 1 μA current reference from 0.35 μm CMOS process show a maximum temperature coefficient of 139 ppm/°C for a temperature range of 0---80 °C. The line regulation is reduced to 0.5 %/V for supply voltage of 3.5 to 5.5 V.

In view of the practical application of battery's internal resistance test, a current source which meets the requirements of the AC impedance test is designed. The current source uses DDS (Direct Digital Synthesizer) technology to generate sinusoidal AC signals at each frequency band and inject them into the improved Howland circuit which is a kindle of voltage controlled current source circuit. After the power amplification of the Howland circuit, sinusoidal AC signals change into the stable sinusoidal AC current which meets the frequency and amplitude requirements. Then the AC current is injected into the battery to test the internal resistance. In this paper, the experimental results show that the designed current source system can produce the required AC current quickly and stably, and reduce the noise interference caused by the instability of the current source in the measurement of battery internal resistance.

The most important problem encountered in Functional Near Infrared Spectroscopy is the loss of stability and reliability of the light emitting diode as a result of an on going heat transfer between the living tissue and the light emitting diode. This condition has an unwanted disruptive effect on the radiated light. Within this study, a current source circuit with temperature feedback is developed to reduce these effects to minimum and preliminary experiments are done with the developed circuit. The developed circuit is an op-amp based constant current source which consists of a digital potentiometer, a temperature sensor and a microcontroller. Regarding the temperature reading, microcontroller manipulates the value of the digital potentiometer, thereby manipulating the current supplied to the light emittng diode by the current source, instantly. Preliminary studies showed that, the circuit developed for operation between 20°C and 46°C temperature values is much more beneficial when compared to a simple current source. In future, manufacturing the circuit in a modular structure is planned for clinical applications. © 2017 IEEE. 21st National Biomedical Engineering Meeting, BIYOMUT 2017 -- 24 November 2017 through 26 November 2017 -- -- 140363

Based on the different types of input and output filters, the single-phase high-frequency link matrix rectifier is divided into voltage source and current source. Respectively, for the voltage and current source circuit proposed de-re-coupling coupled PWM modulation strategy, and the working state of voltage and current source topology in a high frequency period is analyzed in detail. Finally, the simulation results verify the correctness and feasibility of the proposed method.

This paper presents a novel circuit implementation for overcurrent protection of low-dropout voltage regulators, that is able to limit the maximum current the regulator can source into the load to a value set by the user and to keep the current limit value fairly independent of process variation and output voltage, as well as maintaining its temperature drift over the wide temperature range of −50°C to +185°C to below 15%. This is achieved by using an open loop Widlar bandgap structure supplied by an additional current branch, placed in parallel with the power transistor. Design equations are presented in the paper along with electro-thermal simulations that identify the hot spots of the power transistor, thus optimizing the placement of the sense transistor and improving the current sensing accuracy. The proposed circuit is implemented in a standard bipolar junction transistor process. Measurement results — including thermal test scenarios are in good correlation with simulations, thus validating the design.

In this study, p-MOSFETs in floating current source circuit are converted to dynamic threshold voltage MOSFET structure and a second order notch filter application is carried out by using the DTMOS based FCS circuit. The proposed model is simulated in LTSPICE simulator by using Taiwan Semiconductor Manufacturing Company 0,18μm CMOS technology. DTMOS structure allows the operation of the circuit at lower power about 4,95nW. Operating frequency of notch filter consisting of the DTMOS-FCS circuit is set up to suppress the undesirable effects of power-line interference on the electrocardiograph signals.

Carbon nanotube field emission display (CNT-FED) is one of the most significant subjects due to its unique qualities and perfect performance. But there are still some problems in FED, for example, the modulation of each pixel unit of field emission display device is discrete, and the traditional voltage pulse-width modulation driving mode cannot solve luminance non-uniformity and non-linearity of FED. So a novel driving circuit based on cathode current source is proposed. The current driving circuit can be fabricated on Si substrate in advance, and then carbon nanotube is grown at room temperature, carbon nanotube and constant current source circuits are integrated on the same Si substrate. Current source circuit and cathode emission part are integrated together, which not only can solve the FED luminance problem, but also can meet FED thin design.

The mirror current source, with the characteristics of small static resistance and dynamic resistance, has been widely used in the analog integrated circuits, commonly used as a bias circuit and active load [1]. Aiming to the problem of the output signal waveform saturation distortion, which caused by the drift effect when the temperature rises in the fixed bias circuit, this paper provides a circuit design of replacing the collector load resistance of by the mirror current source and carrying out simulation analysis by multisim10 software, compared with the theoretical calculation to verify the rationality of the design circuit.

In order to provide stable and adjustable current source for portable systems, this paper designs a digitally controlled constant current source. According to the input of independent key, the output of the microcontroller digital volume controls digital-to-analog converter by Voltage-Current conversion module to get the constant current output. The output module consists of the operational amplifier and the power transistor TIP122, which is used for voltage-current conversion. At the same time, the value of output current is obtained by sampling resistor to convert the real-time acquisition and monitor the output of constant current source. The experimental results show that the system output ranges from 0 mA to 240 mA. The value of constant current can be controlled by stepper key, and the measurement error ratio can meet the requirement of design.

Magneto-rheological fluid damper is widely driven by current source. The nonlinear factors become inevitable in system performance improvement. This paper mainly put forward and demonstrated a new theoretical model of MRF damper by the method of experimental modeling. Then a current source circuit was constructed with this model by PSpice. At last, the circuit response influenced by load parameters was analyzed, then get the relationships of load parameters and current response time. The research results show the model can characterize the MRF damper load characteristics accurately and the analysis of the load parameters can gave some useful suggestions to the current source design.

In digital phase locked loop cascode structured charge pump is proposed with current mismatch less than 0.01%. Steady state error in digital phase locked loop can be minimized by reducing current mismatch. The rail to rail operational amplifier and cascode current source circuit is employed to reduce the mismatch between charging and discharging current. The operational amplifier has high gain of 90dB. The proposed charge pump is designed, simulated and verified at power supply of 1.8V in TSMC 90nm CMOS technology.

This paper presents a simple solution to realize a 100-A dc current source with high stability. The new source is based on an improved voltage-controlled current source (VCCS) circuit, and a wideband dc current transducer (DCCT) is added for high-current conversion in the feedback loop. The advantage of this modification is that the power consumption on the sample resistor of the VCCS can be greatly reduced, thus the resistor stability can be easily guaranteed. The preliminary measurement results show that the current stability of the designed source is better than 0.5 ppm/h.

In this paper, two low voltage level shifters are designed which are fast and power efficient. The level shifters shift the level from subthreshold to above threshold voltage. The level shifters are designed at 65nm process technology. The first level shifter is designed by replacing the bulk MOSFET with the FD SOI MOSFET using HSPICE simulator. The other level shifter is designed by using SOI MOSFET instead of bulk MOSFET and a widlar current mirror. SOI MOSFET is used in order to reduce leakage currents that are induced due to scaling (reduction in leakage current also reduces the power dissipation in the level shifter). Here, the effects of using widlar current mirror over Wilson current mirror has been studied.

In this paper, a digital control continuous light-emitting laser diode power supply has been present. According to the characteristics of laser diode, the is easy controlled, miniaturization, high efficiency, non-impact and slow-start. The mathematical model of current source circuit and the design method of transform the analog control model to the digital control model is established to improve the performance of laser diode current source. The efficiency of supply is better then 92%.

A novel tuning principle for simple gyrator-based CMOS active inductor (AI) circuit is presented. The method makes use of Widlar current source to enhance the quality factor. The simulation of the proposed AI provides a maximum quality factor of 1819 at 2.88[Formula: see text]GHz. The AI shows the inductive bandwidth of 1.66[Formula: see text]GHz to 3.16[Formula: see text]GHz and power consumption of 6.87[Formula: see text]mW. The other characterization factors such as linearity, supply voltage sensitivity and noise analysis are discussed. The performance of the tunable AI using Widlar current source are compared with the same using a simple current mirror. An AI using a conventional current mirror (CCM) and Widlar current source have been implemented in the 0.18[Formula: see text][Formula: see text]m CMOS technology.

In this paper, a sub-1 V input single-inductor dual-output (SIDO) dc-dc converter with an adaptive load-tracking control (ALTC) technology is proposed for single-cell-powered portable devices. Having a minimal number of switches and an optimum current sequence, the proposed ALTC technique adaptively and accurately adjusts storage energy in the form of inductor current according to the actual load condition, without wasting surplus charge and without increasing cross regulation. Moreover, a current-mode ring oscillator with a self-bias current source circuit, in place of the conventional start-up ring oscillator, is proposed to produce a nearly constant system clock for the requirement of sub-1 V start-up procedure. Because the proposed current-mode ring oscillator operates between the start-up process and steady state of the SIDO dc-dc converter, its simplified design efficiently addresses the high switching frequency losses at sub-1 V start-up procedure, reducing chip area and power consumption. The proposed sub-1 V input SIDO dc-dc converter was fabricated via Taiwan Semiconductor Manufacturing Company 0.25 μm 2.5 V/5 V Bipolar-CMOS-DMOS process, and the experimental results show high efficiency of 92% with a good cross regulation smaller than 10 mV.

In view of the practical problems that exist in the yarn flaws detection circuits, which has employed the traditional DC drive in the industry field, this essay, however, based on the two kinds of Matlab simulation results of the detection circuit that used by DC d rive and sinusoidal drive separately, has designed a photoelectric yarn flaws detection circuit through sinusoidal drive, which , including a 100 kHz sine wave generating circuit, a current source circuit, a infrared sensor, a yarn signal acquisition circuit, a precision full-wave rectification circuit, a differential amplification circuit and so on. Through the experiment and test on site, the photoelectric yarn flaws detection for circuits that driven by sine wave could perfectly meet the requirements of yarn testing standards. Comparing to the DC drive, the sinusoidal drive does better in anti-interference and environmental adaptation.

This paper proposes a design and implementation of wireless temperature monitoring system for shrimp farm based on ZigBee technology. The proposed system consists of three wire resistance temperature device (RTD) type PT-100, Current source circuit, XBee Pro module, 2.4 GHz antenna with gain 5dBi, Arduino Uno R3 microcontroller board and LabVIEW program for monitoring and control system. Experimental results with standard temperature bath show that the proposed system can monitor temperature with satisfied data. The maximum error of temperature is about 0.25 percents. The maximum range of system is about 500 meters.

In tactile scanning profiler, the measuring force would change in a wide range when it was used for profile measurement in a large range, which could possibly destroy the measured surface. To solve the problem, measuring force control system for tactile scanning profiler was needed. In the paper, a voice coil motor-based measuring force control system for tactile scanning profiler was designed. In the design, a low stiffness coefficient spring was used to provide contact force, while a voice coil motor (VCM) to balance the spring force so that the contact force could be kept for constant measuring force. A VCM was designed specially, and for active measuring force control, a precision current source circuit under the control of a DSP unit was designed to drive the VCM. The performance of voice coil motor based measuring force control system had been tested, and its good characteristics were verified.

This paper implements a “multi-tanh principle” to linearize the bipolar differential amplifiers by offsetting the transfer function of the differential pairs and connection them in parallel. The principle is analyzed in detail and the optimum 3.75 and 2.9 offset ratio is found for a double and a 4-cell linearized differential amplifier. The resulted 4-cell linearized amplifier achieves an extremely linear ±20mV dynamic range within less than 0.1 dB ripple. The structure is shouldable for further expansion for wider linear operation. Temperature dependence is discussed and compensation from 250K-400K is realized by implementing the transistor size ratio, the Widlar current source and MOS voltage shift cell. Such differential amplifier with high linearity and insensitivity to stress will be suitable for high frequency situation or accurate gain control in varies of industrial applications.

A new method to reduce power consumption of a linear transconductor is proposed in this paper. The minimum tail current for the operation of the transconductor is supplied by a new current source circuit. The proposed circuit is based on a dynamic biasing current technique. Results of SPICE simulation show that the proposed technique is very effective to reduce power consumption of the transconductor.

The Widlar current mirror, a widely used integrated circuit configuration, normally receives only a superficial treatment in electronics texts. This didactic study consists of a detailed analysis followed by a step-by-step design procedure that takes into account resistor and transistor parameter tolerances, a topic rarely covered in undergraduate/graduate courses.

Bioimpedance measurements have become a useful technique in the past several years in biomedical engineering. Especially, multi-channel measurements facilitate new imaging and patient monitoring techniques. While most instrumentation research has focused on signal acquisition and signal processing, this work proposes the design of an excitation current source module that can be easily implemented in existing or upcoming bioimpedance measurement systems. It is galvanically isolated to enable simultaneous multi-channel bioimpedance measurements with a very low channel-coupling. The system is based on a microcontroller in combination with a voltage-controlled current source circuit. It generates selectable sinusoidal excitation signals between 0.12 and 1.5 mA in a frequency range from 12 to 250 kHz, whereas the voltage compliance range is ±3.2 V. The coupling factor between two current sources, experimentally galvanically connected with each other, is measured to be less than −48 dB over the entire intended frequency range. Finally, suggestions for developments in the future are made.

Multi-frequency electrical impedance tomography has been evolving from the frequency-sweep approach to the multi-frequency simultaneous measurement technique which can reduce measuring time and will be increasingly attractive for time-varying biological applications. The accuracy and stability of the current source are the key factors determining the quality of the image reconstruction. This article presents a field programmable gate array-based current source for a multi-frequency simultaneous electrical impedance tomography system. A novel current source circuit was realized by combining the classic current mirror based on the feedback amplifier AD844 with a differential topology. The optimal phase offsets of harmonic sinusoids were obtained through the crest factor analysis. The output characteristics of this current source were evaluated by simulation and actual measurement. The results include the following: (1) the output impedance was compared with one of the Howland pump circuit in simulation, showing comparable performance at low frequencies. However, the proposed current source makes lower demands for resistor tolerance but performs even better at high frequencies. (2) The output impedance in actual measurement below 200 kHz is above 1.3 MΩ and can reach 250 KΩ up to 1 MHz. (3) An experiment based on a biological RC model has been implemented. The mean error for the demodulated impedance amplitude and phase are 0.192% and 0.139°, respectively. Therefore, the proposed current source is wideband, biocompatible, and high precision, which demonstrates great potential to work as a sub-system in the multi-frequency electrical impedance tomography system.

The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

In this chapter, we discuss a more detailed incremental model of the bipolar transistor that takes into account the base-width modulation effect. The resulting resistive elements resulting from base-width modulation have significant design impact on high-gain amplifiers, emitter-followers, and current mirrors.

A current mirror circuit is widely utilized as an important building block in analogue signal processing circuits. This paper describes a high-precision low voltage bipolar current mirror circuit. Well known current mirror circuits, such as a simple current mirror and a Wilson current mirror, have a trade-off between low-voltage operation and accuracy of the current gain. The accuracy of the proposed current mirror is high in spite of low current amplification factor (β) of transistors and large current output (or a large number of the multiple output). The current mirror circuit can operate at a 1V or less supply voltage. The high accuracy is realized by negative current feedback with high gain. Thus, the stability of the circuit and compensation methods are discussed. PSPICE simulation shows that the proposed current mirror circuit compensated using Miller components composed of a capacitor and a resistor is stable and can operate at a 1V supply voltage.

Circuit design techniques for very low-voltage bias circuits are discussed. A Nagata current mirror is very suitable for battery operation because it provides current regulation. Also, it is very suitable for start-up circuitry. In this brief, an inverse Widlar current mirror is newly proposed as a nonlinear current mirror with a negative temperature coefficient (TC), a Nagata/inverse-Widlar current mirror is also proposed as a Nagata current mirror or an inverse-Widlar current mirror with an optionally programmed positive or negative TC, and a TC shifter with an offset voltage proportional to absolute temperature (PTAT) is also proposed. Furthermore, fundamental characteristics and temperature characteristics of the bias circuits discussed in this brief were verified with transistor-arrays and discrete components.

A new current source for low-voltage applications is proposed. This current source is well suited for biasing differential pairs and source followers. Measured compliance voltage is slightly smaller than that of a single transistor. Its output resistance is a factor of 25 larger than that of a single transistor current source and was measured to be 8 M/spl Omega/. The use of the new current source improves the common-mode input range and the common-mode rejection ratio of fully balanced and single-ended differential amplifiers.

This work presents a temperature and process insensitive CMOS transistor only reference current generator. In the proposed scheme, the passive resistor used in the CMOS Widlar current source is replaced with a transistor resistor where the gate voltage is controlled so that the output current is insensitive to temperature variation. Furthermore, to maintain the temperature insensitivity under process variations, the transistor resistor gate bias circuits optimized for nominal, strong and weak process corners are built on-chip. The proposed reference current generator is designed using 0.5 μm CMOS SOI technology, where the operation is verified through circuit level simulations under nine different process corners. The 20 μA reference current shows a temperature coefficient of 39 ppm/°C within the temperature range of 25°C ~ 125°C for the nominal process corner.

A CMOS voltage reference without resistor is designed and simulated in SMIC 0.18μm CMOS process in this paper. Simulation results show that the power supply rejection (PSRR) of the voltage reference at 10Hz, 100kHz and 10MHz achieves, respectively, 44dB, 44dB and 37dB. When temperature is in range from -50 to 99°C, the voltage reference achieves an output voltage of about 1.21V with a variation of ±25mV.

We investigate the impacts of the single charged trap induced Random Telegraph Noise (RTN) on the analog properties of FinFET and Trigate devices. A comprehensive comparative analysis between FinFET and Trigate device is carried out for the trap located along the channel length and fin height direction employing 3D atomistic TCAD simulations, and the resulting impacts on g m , r o , f T and Wildar current source examined. The results indicate that Trigate device, with larger (smaller) fraction of electron current flowing near the bottom (top) region of the fin, suffers larger (smaller) RTN degradation when the trap is located at the bottom (top) region of the fin. As such, the RTN amplitude in Trigate device has broader dispersion and stronger dependence on the location of the trap compared with FinFET device. For trap positioned along the channel length direction, the single trap located near the source region has the largest influence on the output resistance (Δ ro /r o ) when the device operates at saturation region (V D = 1V), because the sensitivity of ID to ΔV D becomes higher as the potential barrier for carrier injection near the source is significantly perturbed. The variability of RTN Δg m /g m under fin Line Edge Roughness (LER) and Work Function Variation (WFV) is examined, and Trigate device is shown to exhibit larger nominal Δg m /g m and larger s(Δg m /g m ). The Widlar current source is used as an example to illustrate the impacts of RTN on analog circuit. The combinations of trapping/detrapping in the current source device and mirroring/output device, and the dependence of ΔI out /I out on their VGS difference are examined. The Trigate device exhibits larger ΔI out /I out and larger s(ΔI out /I out ), and the difference between Trigate and FinFET becomes more significant with decreasing gate over-drive.

The secondary instrument calibrator is mainly used for testing and calibrating the temperature or flux measuring meters used in engineering projects. In this paper, we mainly describe the design and implementation process of it. The Mcs51 microprocessor of the Intel Corporation, 5 – 1/2 bits A/D converter with micro-processor, and LCD module are used in our design. Furthermore, standard current source circuit and control circuit must be considered. On one hand, the calibrator can be used as a voltmeter or ammeter. On the other hand, it can provide high precision current source for the calibration of secondary instruments.

We propose an ultra-low power thermal sensor consisting of a nano-ampere CMOS current source circuit and a single bipolar transistor. Since the stability of current source circuits is the most important issue for our thermal sensor, we developed a circuit with an improved process and temperature stability. Our simulations and the measurements we conducted on the proposed thermal sensor demonstrated that it can be robustly operated in a wide temperature range. The power dissipation of the circuit was 105 nW for a 3-V power supply. The accuracy was within ±1°C in a wide temperature range of −20 to 120°C.