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There has been significant recent progress in the implementation of integrated non-reciprocal components based on linear periodically time-varying (LPTV) circuits. Nevertheless, integrated circulators still require a leap forward in power handling, clock power consumption, and insertion loss (IL) to become compelling compared with ferrite circulators or integrated reciprocal alternatives, such as the electrical-balance duplexer (EBD). This article introduces three innovations: 1) a new switched-capacitor clock-boosting scheme; 2) high-Bragg-frequency quasi-distributed transmission lines based on periodically loaded inductors; and 3) a new gyrator based on switched partially reflecting t-lines—which enable significant performance improvement for integrated circulators and for LPTV circuits more broadly. These are showcased in a 1-GHz 180-nm SOI CMOS circulator that exhibits 2.1-/2.6-dB TX-ANT/ANT-RX IL (0.3 dB better than prior art), +34-dBm TX-ANT P1 dB (2.5 $\times $ or 4 dB better), and 40% lower chip area, all at 39-mW power consumption (4.4 $\times $ lower).

This article proposed a novel scheme integrating full-duplex communication into high-power wireless power transfer systems. The power and data are transferred through the same inductive link. A pair of coupling coils with taps are employed to omit the trap inductors that are widely employed in former simultaneous wireless power and data transfer (SWPDT) systems. The proposed scheme can reduce the system cost and size and improve the power transfer efficiency. The power and bidirectional data are transmitted using carriers of different frequencies. Frequency division multiplexing technique is utilized for full-duplex communication. The duplexer is carefully designed to separate the transmitted and received data signals. The circuit model of the system is built to analyze the power and data transfer performance. The crosstalk between the power and data transfer is also discussed. To improve the performance of data transfer, the method to determine the optimal coil tap position is proposed. A 300-W SWPDT prototype with a full-duplex data rate of 500 kb/s was built to demonstrate the feasibility of the proposed system.

A 28-GHz in-band full-duplex (IBFD) power amplifier (PA) is presented which integrates a PA with an impedance matched hybrid transformer in a 28-nm bulk CMOS process. The hybrid transformer has a 1:2 turn ratio to match from the optimum load impedance of $25~\Omega $ for a PA to the antenna and balance ports of $100~\Omega $ . Since this allows the additional matching circuits of a PA and an antenna to be obviated, the full-duplex loss is reduced. It shows 28.4-dB isolation between the PA and LNA ports at 28 GHz. For comparisons, a 50- $\Omega $ matched PA and an IBFD PA are designed. The IBFD PA has core sizes of $0.24\times 0.43\,\,{\text {m}}{\text {m}}^{2}$ . Since the impedance matched hybrid transformer has the similar size to the output matching network of the 50- $\Omega $ matched PA, a full duplexer is integrated into the PA without additional chip area. The IBFD PA has 10.6-dB gain and a drain efficiency of 8.9% at 12.3-dBm P1dB.

In this paper, a compact bandpass filter with improved band stop and band pass characteristics for wireless applications is built with four internal conductive poles in a single resonating cavity, which adds novel quad-resonating modes to the realization of band pass filter. This paper covers the design and testing of the S-band combline coaxial cavity filter which is beneficial in efficient filtering functions in wireless communication system design. The metallic cavity high Q coaxial resonators have the advantages of narrowband, low loss, better selectivity and high potential for power handling, as compared to microstrip filter in the application to determine the quality factor of motor oils. Furthermore, the tuning of coupling screws in the combline filter allows in frequency and bandwidth adjustments. An impedance bandwidth of 500 MHz (fractional bandwidth of 12.8%) has been achieved with an insertion loss of less than 2.5 dB and return loss of 18 dB at the resonant frequency. Four-pole resonating cavity filters have been developed with the center frequency of 4.5 GHz. Insert loss at 0 dB and estimated bandwidth at 850 MHz and a quality factor of 4.3 for the band pass frequencies between 4 and 8 GHz is seen in the simulated result.

This article presents the results of development and optimization of a new square waveguide polarizer with diagonally located square irises. The application of suggested geometrical modification of irises form and location instead of a standard wall-to-wall irises configuration allows to exclude 45-degree twists between wideband waveguide polarizer and orthomode transducer of a dual-polarized antenna feed system. In addition, a waveguide polarizer and polarization duplexer can be manufactured by milling technology as two single details, which makes the proposed engineering solution reliable, simple for simulation, development and application. Suggested new polarizer design was developed for the satellite operating Ka-band. It contains 12 irises, which are symmetrically located in the diagonal corners of a square waveguide. Obtained optimal polarization converter provides excellent matching and polarization performance. The maximum level of VSWR is less than 1.04 for both orthogonal polarizations. Values of cross-polarization discrimination are higher than 32 dB in the operating Ka-band. Developed square waveguide polarizer with diagonally located irises can be applied in modern wideband satellite antennas.

This study presents the first monolithically integrated full-duplex front-end for K/Ka satellite communication phased arrays. A 0.25 μm SiGe:C BiCMOS process was used to develop the integrated circuit. The receive and transmit channels are united into a common port through a novel duplexer. For each RF channel, the bias currents, the active channels and the power amplifier operation mode can be controlled through a serial bus. Amplitude and phase control are provided with fine granularity (65,536 states). In transmit mode, each channel provides 37.3 dB of gain with 12.9 dBm output power at 1-dB compression. In receive mode, 33.7 dB gain is measured with a noise figure of 3.2 dB. The amplitude/phase root-mean-square errors within the transmit (29.5–30.8 GHz) and receive (19.7–21 GHz) bands are below 0.7 dB/ 6.4 ° and 0.26 dB/ 1.1 ° , respectively. The chip occupies 1.64 × 3.5 m m 2 and it consumes 81 and 15.5 mW per transmit and receive channels, respectively. The use of a Doherty power amplifier with a novel dynamic adaptive bias circuit led to a 31% reduction of the total dc array power consumption.

Tunable duplexers based on self-interference cancellation present a promising alternative to fixed-frequency duplexers (e.g. surface acoustic wave devices), however the level of transmit-to-receive (Tx-Rx) isolation they provide is typically lower compared to acoustic devices. This paper quantifies the impact of reduced isolation on receiver (Rx) noise figure (NF), and determines minimum isolation requirements for Tx-Rx isolation in cellular handset transceivers. Measurements of Tx noise power spectral density from a cellular handset power amplifier are combined with theoretical analysis and long term evolution (LTE) downlink throughput simulations to assess the impact of isolation on the noise figure and sensitivity. Although lower duplexer isolation can lead to substantial desensitization for some duplex separation/bandwidth combinations, achieving LTE compliant sensitivity requires only 38 dB of isolation in the Rx band. LTE sensitivity specification compliance is therefore readily achievable with current tunable duplexing technologies.

In this type of radar pulses only have one antenna that is used to transmit and receive signals, it requires a duplexer that will function as a separator for both signals, this duplexer will isolate the transmitted signal and the received signal. The main component of the duplexer that plays a role in the regulation of isolation is the Coupler which is abbreviated as coupler. The performance of the Coupler can be seen from the characteristics of the parameters it has, namely: Isolation Characteristics, Insertion Loss, Return Loss, and Power Coupling. In this study, changes in the dimensions of the Coupler, changes in this size will affect the value of the isolation. If the isolation value gets smaller, the duplexer performance will be better. Coupler in this study is applied in the form of microstrip and substrate used FR-4 with a dielectric constant of 4.6, 1.3 mm thick and 3 GHz operating frequency. To do this work is done with the 2014 CST simulation software, from the results of simulation experiments obtained the isolation value of -67.786 dB.

Active FSS (Frequency Selective Surface) for Wireless Applications have been explored and presented. In this paper, I-shaped, PIN diode loaded frequency selective surface with FR-4 substrate is proposed for duplexer applications with switching of PIN diode ‘in ON state or in OFF’. FSS with regular pattern using I-shaped cell has been analysed for multiple frequency bands. Using five I-shaped unit cells, three multiple frequency pass band for Tx frequencies and stop band for Rx frequencies and vice a versa have been obtained in the two switching bands. Four frequency bands with Nine I-shaped unit cells have also been presented for duplexing applications. HFSS v12 software has been used for analysis of the structure.

In this paper, a compact microstrip duplexer with relatively close channels is proposed. The ring resonator and the orthogonal-feed are directly connected to form a band elimination filter. The band elimination filter is loaded with branches to realize the band-pass filter. The design of the duplexer in the article composed of two such band-pass filters. The design method of the duplexer is introduced in detail, and verified by the experimental results of the manufactured duplexer. The central frequency of the bandpass channels is 1.45Ghz and 1.75Ghz respectively. The measurement results show that the two channels of the duplexers are close to each other, with low insertion loss and high out-of-band rejection, which are in good agreement with the simulation results.

This paper describes the design of an integrated duplexer with electrical balance network using the phase locked loop (PLL) for impedance variation tracking. The hybrid transformer is devised for blocking the transmitted signal leaking to the receiver. We suggest a method of impedance tracking based on PLL system, which can maintain high isolation between the transmitter and the receiver. The PLL is employed to sense the transmitter leakage continuously and tune the impedance of the electrical balance network adaptively in real time. The isolation between the transmitter and the receiver is maintained almost constantly in a range of capacitances used in the antenna model, compared with that without the phase locked loop. The return loss at the transmitter port and the insertion loss from the transmitter to the antenna port are measured 30 dB and 6.9 dB at 1.95 GHz, respectively. The planar inverted-F antenna (PIFA) model is used for simulating and measuring antenna and electrical balance network. A capacitor value comprising the PIFA is varied and the proposed duplexer is investigated, leading to automatic impedance tracking in some range.

In this paper, a highly integrated frequency-modulated continuous-wave (FMCW) radar system with a single-antenna interface for range sensing is proposed. In this paper, a circulator structure was developed and used in the radar system with the single-antenna interface. This structure capitalizes on frequency orthogonality to separate transmitted and received signals; thus, the isolation can be improved by using integrated filters to further suppress transmitter leakage. Without an additional back-end leakage cancellation mechanism and antenna tuner, the single-antenna FMCW radar system can be devised. The proposed system is composed of a radar transceiver, a frequency synthesizer, an analog signal processor, and an AD converter; the system is fabricated using a 65-nm CMOS technology, occupies a chip area of 1.9 mm2, and consumes 147-mW dc power under a 1.2-V power supply. The implemented front-end circuit can provide an output power of 10.5 dBm with power efficiency of 30%, over 1-GHz impedance matching, an insertion loss of 2 dB, a maximum noise figure of 16.8 dB (including the following IF amplifier), $P_{1\,\text {dB}}$ of 2 dBm, and IIP3 of 7 dBm. A wireless measurement process proved that the system can provide a 37-cm range resolution over a 50-m range for a $20 \times 20$ cm2 copper plate. Finally, an FMCW radar front-end board and a digital signal processing board were implemented for data analysis, thus completing the FMCW radar sensor unit. The proposed system can be utilized for multiple applications including 1-D object tracking, 2-D localization, and 3-D object tracking.

Three different bidirectional polymer microwave fiber (PMF) links are presented and discussed. The proposed solutions exploit the following orthogonal signaling dimensions: wave direction, wave polarity, and signal polarity. First, a 120-GHz substrate integrated waveguide directional coupler is implemented and exploits the wave direction orthogonality. The 4-port on-board hybrid coupler achieves measured data rates of, respectively, 6 and 5.5 Gbps in the up- and down-link over a distance of 8 m. Second, a 120-GHz ortho-mode transducer (OMT) is micro-machined and exploits the wave polarity orthogonality. The micro-machined polarization duplexer has a measured isolation of 45 dB over the entire $F$ -band. For the horizontal and vertical paths, the insertion loss is measured with a 40-cm-long Teflon fiber and varies between −5 and −9 dB. Finally, a 120-GHz in-band full-duplex (IBFD) PMF transceiver with tunable electrical-balance duplexer (EBD) and on-chip bow-tie antenna are implemented in a 40-nm bulk CMOS technology. In this case, the duplexing principle is relying on signal polarity. The self-interference (SI) cancellation is achieved with a fully differential transformer-based EBD, resulting in a simulated SI suppression of 30 dB over a bandwidth of more than 14 GHz. The insertion loss of the duplexer is less than 11 dB from TX to fiber and less than 12 dB from fiber to RX at a frequency of 120 GHz. The balancing network provides an impedance locking range from 45 to 93 $\Omega $ and 38 to 266 fF at 120 GHz. For IBFD operation, the maximum measured data rate is 6.2 Gbps. The transceiver with integrated antenna occupies an area of 1.8 mm $\times $ 1.53 mm and has a dc power consumption of 73 mW in total.

This paper proposes a surface-acoustic wave (SAW)-less tunable RF front end (RF-FE) using an electrical-balance duplexer (EBD) integrated with a switched-LC N-path low-noise amplifier (LNA). The EBD cancels the transmitter–receiver (TX–RX) leakage at the RX frequency by dynamically optimizing the balance of a hybrid transformer, which enables in-band full-duplex (IBFD) operation. A transconductor-based LNA in parallel with a switched-LC N-path network creates input and output notches to reject TX leakage for frequency-division duplexing (FDD) operation. The LNA’s signal-handling capability is enhanced via optimum switch biasing. Fabricated in 0.18- $\mu \text{m}$ SOI CMOS, the RF-FE offers >50-dB tunable rejection from the TX port to LNA output at both TX and RX frequencies, for all 3GPP bands from 0.7 to 1 GHz (i.e., FDD case). It is the first tunable RF-FE including an LNA that achieves +70-dBm TX-path IIP3, and +30-dBm in-band TX power while cancelling the self-interference by >50 dB (i.e., IBFD case). The RF-FE consumes 62.5 mW at 1 GHz with 11.7-dB RX cascaded NF, 3.6-dB TX insertion loss, and 9.62 mm2 active area.

A dual-band CMOS duplexer employing a switchable autotransformer is proposed for highly integrated RF front ends in mobile phones. Because on-chip switches are used to change the length of the autotransformer, the inductance is sized for two different frequency ranges. It is designed to support both low-band (LB) mode from 0.7 to 0.9 GHz and mid-band (MB) mode from 1.7 to 2.0 GHz for cellular applications. With different inductances for LB and MB modes, transmitter (TX)-to-receiver (RX) isolation is achieved by using two separate balance networks for LB and MB. The duplexer is implemented in a 65 nm CMOS process. In LB mode, TX and RX insertion losses (ILs) are less than 4.3 dB, while TX-to-RX isolation is more than 50 dB. In MB mode, TX IL and RX IL are less than 4.5 dB, while TX-to-RX isolation is more than 50 dB. The proposed duplexer proves feasible structure to cover both LB and MB frequency ranges in cellular 3G/4G applications.

A tunable G-band frequency-modulated continuous-wave radar system has been developed and used to perform differential absorption atmospheric humidity measurements for the first time. The radar’s transmitter uses high- power-handling GaAs Schottky diodes to generate between 15–23 dBm over a 10-GHz bandwidth near 183 GHz. By virtue of a high-isolation circular polarization duplexer, the monostatic radar’s receiver maintains a noise figure of about 7 dB even while the transmitter is on. With an antenna gain of 40 dB, high-SNR detection of light rain is achieved out to several hundred meters distance. Owing to the strong spectral dependence of the atmospheric absorption over the upper flank of the 183-GHz water absorption line, range-resolved measurements of absolute humidity can be obtained by ratioing the rain echoes over both range and frequency. Absorption measurements obtained are consistent with models of atmospheric millimeter-wave attenuation, and they demonstrate a new method for improving the accuracy of humidity measurements inside of clouds.

In this study, the design and analysis of a seven-port radar duplexer for tracking a target in X-band operation are presented. The S-parameters of the structure are calculated and compared with experimental results. The simulations and experimental results are in good agreement. This device enables radars to calculate the horizontal difference, vertical difference, and sum of four beams of a monopulse antenna based on amplitude discriminator. Three magic-Ts and one T-junction are used, four input ports are connected to a monopulse antenna and three other ports are output ports. The output data give three equations between input signals that allow the radar to track a target. Results show that the S-parameters of this device are affected by magic-Ts and the T-junction structure, and an optimum structure for the magic-Ts and T-junction is proposed. A comprehensive study has been carried out for determination and comparison of properties of the structure in theory, simulation, and experimental results. This device is useful in radar tracking systems.

A novel voltage controlled duplexer-integrated leaky-wave antenna, consisting of an array of traveling-wave resonant particle by metal ring resonator with variable capacitance and uni-lateral component is proposed, analysed, and measured. In contrast to ferrite-based leaky-wave antenna, this antenna does not require a biasing magnet but only an bias voltage for the FETs, and beam steering voltage for varactor diodes. Bias voltage beam steering in addition to unique duplexer operation is confirmed numerically and experimentally. As a result, beam scanning property from â30° to 45° is realized for 7 GHz operation. One non-conventional property of this antenna is non-reciprocity, and duplexer integrated operation is also confirmed just in one antenna element by utilizing non-reciprocity. Keywords: Artificial magnetic gyrotropy, Non-reciprocity, Magnet-less magnetic metamaterial (MNM), Leaky-wave antenna, Beam-steerable, Integrated device

This paper proposes an adaptive RF front-end (RFFE) architecture that uses an electrical-balance duplexer (EBD) and tuned surface acoustic wave (SAW) resonators to enable adaptive dual-frequency isolation suited for LTE’s frequency-division duplex (FDD) mode of operation. Alternatively, in the in-band full-duplex (IBFD) mode, the EBD cancels the in-band TX self-interference directly at RF for increased channel capacity. Furthermore, the EBD’s balance network is optimized to reduce the TX insertion loss (IL) below the nominal 3-dB limit in the FDD mode. A 0.18- $\mu \text{m}$ SOI CMOS prototype implements the EBD, low-noise amplifier, and SAW-tuning capacitor banks. The chip is mounted to a module substrate together with the SAWs and matching components. The RFFE achieves >50-dB dual-frequency isolation and 2.6–3.4-dB TX IL in FDD mode, has +58/+42-dBm TX/RX-path IIP3 for an increased IBFD-link budget and handles up to +27.5-dBm TX power in both modes.

Electrical balance duplexers (EBDs) present a potential alternative to the fixed-frequency duplexing filters used for frequency division duplexing in cellular handset radio frequency front ends. However, the transmit-to-receive (Tx–Rx) isolation can be affected by interaction between the antenna and the environment, and therefore, the EBDs balancing impedance must adaptively track time-domain antenna impedance variation. A rail scenario presents a potentially demanding use case for an EBD, as fast moving trains in the vicinity of the antenna may cause dynamically changing reflections, which can be received as self-interference. In this paper, measured dynamic antenna reflection coefficients at 745 and 1900 MHz from train mounted antennas are included in the EBD circuit simulations in order to investigate the resulting variation in Tx–Rx isolation, and determine requirements for balancing impedance adaptation. This paper also presents the results from rail-based field trials of a hardware prototype EBD, which implements real-time antenna impedance tracking. Results show that the rail scenario does result in variation in Tx–Rx isolation, but that rebalancing the EBD at the intervals of 5 ms was sufficient to maintain >50 dB isolation for ~95% of the time.

There has been significant recent progress in the implementation of integrated non-reciprocal components based on linear periodically-time-varying (LPTV) circuits [1], [5]. Nevertheless, integrated circulators still require a leap forward in power handling, clock power consumption, insertion loss (IL), and chip area to become compelling when compared with ferrite circulators or integrated reciprocal alternatives, such as the electrical-balance duplexer (EBD) [6]. This paper introduces three innovations - (i) a switched-capacitor clock-boosting scheme, (ii) high-Bragg-frequency quasi-distributed T-lines based on periodically loaded inductors, and (iii) a gyrator based on switched partially reflecting T-lines - that enable such a leap for integrated circulators and for LPTV circuits more broadly. These are showcased in a 1GHz 0.18µm SOI CMOS circulator that exhibits 2.1/2.6dB TX-ANT/ANT-RX IL (0.3dB better than prior art [4]), +34dBm TX-ANT P1dB (2.5x or 4dB better), and 40% lower chip area, all at 39mW power consumption (4.4x lower).

A novel design procedure for waveguide duplexers using stepped E-plane bifurcated junctions is presented. First, a simple model of this junction is devised, suited for the synthesis of star-junction diplexers (a novel procedure has been developed). The characteristic polynomials of the channel filters obtained by this procedure are then employed for the synthesis of the channel filters. To allow transmission zeros in the response, an in-line topology with frequency-dependent (resonant) couplings is adopted. The filters are synthesized with a recently proposed technique (here adapted for waveguide implementation). Furthermore, a new type of resonating coupling structure is adopted (the stopband singlet), allowing the positioning of the transmission zeros very close to the passband. The novel design technique is demonstrated with a Ka-band duplexer for satellite applications.

A type of wide-band signal-interference planar duplexer with single- and dual-band channels is presented. It exploits transversal-signal-interference-section-based channels with contiguous single- and dual-passband filtering transfer functions. Furthermore, by ending the dual-band channel in a reference-impedance resistor, a wide-band bandpass filter (BPF) with quasi-absorptive stopbands is realised. As experimental validation, microstrip prototypes of a duplexer and a two-stage quasi-absorptive BPF that operate in the 1.6–4.4 GHz range are built and tested.

Advances in permanent magnet technology has seen more reports of sensor applications of low field magnetic resonance. Whilst most are either in the 10–20 MHz range or in the earth’s field, measurements at below 1 MHz are beginning to become more widespread. This range is below the need for careful radio frequency electronics design but above the audio domain and represents an interesting cross over. Many commercial spectrometers do not include the pulse power amplifier, duplexer and preamplifier as these depend on the frequency range used. In this work we demonstrate that, with the current specifications of the humble operational amplifier, the most simple form of an inverting design using only two resistors and decoupling, can effectively provide this ‘front end’ electronics. The low powers used mean crossed Ge diodes provide an excellent duplexer and it is suitable for battery powered applications.

This paper presents a D-band transceiver utilizing a 70-nm GaAs metamorphic high electron mobility transistor (mHEMT) technology for a frequency division duplex (FDD) system. The transceiver includes a duplexer, transmitter and receiver modules, an LO and IF circuit board, and a real-time modem. Each module comprises a silica-based package on which D-band converter and E-band multiplier monolithic microwave integrated circuits (MMICs) are mounted using a flip-chip bonding technique. Real-time communication tests are performed at 142- and 157-GHz duplex frequencies. A 10-Gbps transmission with a high spectral efficiency are achieved using a 128 quadrature amplitude modulation (QAM) signal.

This paper describes a spurious noise measurement arising from radio frequency integrated circuit (RFIC) and an analysis of its impact on receiver of a 4G cellular mobile handset. In mobile radio systems, there are two types of unwanted signals that degrade the receiver sensitivity: phase noise and spurious clock noise arising from an RFIC. The former noise is observed by band power measurement. However, the latter one is not easily observed by the same way because it is a tone signal with varying phase noise. To detect the spurious clock noise, measurement system with combination of an active probe, inter-stage filter with high attenuation (80 dB) and spectrum analyzer with low floor noise (-155 dBm/Hz) is proposed. As a result, the spurious clock noise in a mobile handset in communication state (LTE-Band I) was observed as intended. The measured spurious noise exceeded phase noise about 10dB. To maintain sufficient receiver sensitivity, and high isolation duplexer more than 65 dB is therefore required.

The use of in-band full duplex (IBFD) is a promising improvement over classical TDD or FDD communication schemes. To enable IBFD radios, the electrical balance duplexer (EBD) has been proposed to suppress the direct self-interference (SI) at the RF stage. The remaining SI is typically assumed to be canceled further in the digital domain. In this paper, we show that the non-zero Doppler frequencies can be extracted from the residual SI, giving information about the speed of objects in the environment. As a result, an IBFD radio can be seen as a monostatic Doppler radar which is affected by the communication signal. This paper presents a detailed performance analysis of the different sources of interference affecting the Doppler radar. The performance is also evaluated using a radar-enhanced IBFD prototype consisting of a SDR module and an EBD designed to achieve up to 55 dB Tx-Rx isolation in the 1.74 GHz RF band. A measurable Doppler component is created by moving a 15 dBsm cone at known velocities at 0. 5-1.3 m from the prototype. For an EBD SI rejection of 45 dB, speeds in the range of 200 to 800 mm/s are detected with high accuracy.

Duplexers based on self-interference cancellation can provide substantial transmit-to-receive (Tx-Rx) isolation, whilst being tunable over wide frequency ranges, presenting a promising alternative to fixed-frequency acoustic duplexers commonly used in today's mobile devices. However, the level of Tx-Rx isolation provided by tunable duplexers is typically lower compared to surface acoustic wave and bulk acoustic wave devices. This paper investigates the impact of reduced isolation on receiver (Rx) noise figure (NF), and quantifies the minimum requirement for Tx-Rx isolation in a long term evolution (LTE) mobile terminal. Tx noise in the Rx band is quantified through measurements taken from a cellular handset power amplifier, for a range of duplex separations and uplink bandwidths, and combined with a simple linear model to calculate the desensitized Rx NF as a function of Tx-Rx isolation. LTE downlink throughput simulations are used to assess the impact of isolation on LTE sensitivity, and establish the minimum isolation required for LTE sensitivity specification compliance. Results show that reduced duplexer isolation leads to substantial desensitization for some duplex separation/bandwidth combinations, however, to achieve the minimum LTE sensitivity requires only 38 dB of isolation in the Rx band; this is achievable using current tunable duplexing technologies.

An electrical-balance duplexer achieving the state-of-the-art linearity and insertion loss (IL) performance is presented, enabled by a partially depleted RF silicon-on-insulator CMOS technology. A single-ended configuration avoids the common-mode isolation problem suffered by topologies with a differential low-noise amplifier. Highly linear switched capacitors allow for impedance balancing to antennas with

The desire for higher magnetic resonance sensitivity has led to the development of multiple home-built and commercial dissolution dynamic nuclear polarization polarizers. The emergence of polarizers capable of variable magnetic field strengths desires a versatile standalone spectrometer and NMR circuit to fulfill detection needs at different frequencies. We present a benchtop NMR spectrometer with a duplexer capable of serving high-field solid and liquid state NMR applications up to 450 MHz. A detailed view of the employed probe is discussed. Tuning and matching schemes are investigated yielding and experimentally verifying closed-form equations to estimate the nutation frequency for a remotely tuned and matched sample coil.

Partially depleted silicon-on-insulator (PD-SOI) is a key enabling technology for adaptively tuned RF front-end modules (FEM). Unlike bulk CMOS, thanks to SOI's insulating buried-oxide (BOX) layer, switched capacitor banks can allow for large voltage swing and exhibit a high small-signal linearity. This in turn enables LTE standard-proof power and linearity capabilities for tunable duplexers based on electrical-balance duplexers (EBDs) and N-path filters. These building blocks help to reduce the amount of SAW filters typically required in LTE handsets and enable in-band full-duplex (IBFD). This paper presents an overview of work related to tunable FEM in 180nm PD-SOI technology.

Phase matching of ladder-type filters based on micro-acoustic technology is an important part of duplexer and multiplexer design. However, it cannot be straightforwardly applied in direct bandpass synthesis methodologies because of essential differences between lowpass and bandpass approaches. A novel filtering function able to accommodate a new phase control term is proposed in this paper. Taking into account the phase correction from the beginning of the synthesis provides additional advantages in the network design.

A class of frequency-tunable planar multiplexer with quasi-reflectionless behavior at its input port for modern RF wireless-communications transceivers is presented. To attain the input quasi-absorptive characteristic in a Kth-order N-channel realization, an additional Kth-order N-band multi-stopband channel terminated in a reference-impedance resistor is added. Each Kth-order stopband in this N-band bandstop channel exhibits a nearly-complementary frequency profile with regard to the one of a counterpart bandpass channel. Thus, the input-signal energy not transmitted by the bandpass channels in their stopband regions is dissipated in the resistor of the nearly-complementary multi-band bandstop branch. The theoretical operational principles and coupling-matrix-based design equations for the first-order input-quasi-reflectionless multiplexer stage are detailed. Furthermore, for experimental-validation purposes, a first-order microstrip duplexer prototype that can be tuned in the 0.85–1.15-GHz range is manufactured and characterized.

The isolation between transmitter and receiver for the radars is ultimately important since the transmitting radar signals can be penetrated the receiver directly in case a bad isolation is formed. This paper describes the isolation between the transceiver and the design of an integrated full duplexer using the phase locked loop (PLL). Although the antenna impedance varies arbitrarily, the PLL tracks the impedance variation in real time, leading to improvement of isolation between the transmitter and the receiver of radars. The full duplexer reduces the transmitter leakage up to 45 dB using the balance network along with the PLL in measurement.

We present a 220 GHz imaging radar prototype that has been developed in the European Defense Agency (EDA) project TIPPSI. The purpose of the development was to demonstrate short-range high-resolution 3D imaging for security applications at checkpoints, and to guide the development of stand-off real-time millimeter wave and sub-millimeter wave imaging systems for detection of larger objects at greater distances. An additional goal was to experimentally verify simulation techniques for active (sub)-mmw imaging systems, the verified simulation techniques can then be used to explore different system architectures. The 220 GHz imaging radar prototype consist of a flexible, mechanically scanned optical system that can support linear arrays of transmit/receive (TxRx) units up to 150 mm in length. The optical system is divided into two parts: A compact Dragonian system including the mechanical scanner that can be used as a stand-alone imager at reduced target distance and resolution, and a confocal system that can be added to achieve the full resolution of 1 cm x 1 cm x 1 cm at 4.5 m target distance. The field of view of the full resolution system is 70 cm x 70 cm. The front-end is currently populated by 4 TxRx units that are sparsely distributed along the 150 mm focal plane. The TxRx units operate in frequency modulated continuous wave (FMCW) mode and have a bandwidth of 24 GHz. Each TxRx unit use a single horn antenna and the transmit- and receive signals are generated and received using the same circuits which avoids the need of a duplexer. We will demonstrate high resolution 3D videos taken at 1 Hz frame rate and compare the individual images with simulations using electromagnetic simulators and character/clothes animation.

This paper introduces the design of a broadband switch duplexer. The switch duplexer is used in the microwave measurement instrument. Series-parallel structure of PIN diode is used in the design of switch. Series structure is used in high frequency band, parallel structure is used in low frequency band, and the micro-strip matching circuit is adopted in coupled inductor. Diplexer circuit has many advantages such as low loss, high frequency division point, working at wide-band range, etc.

We conceptually designed a robust nano-scale waveguide structure suitable for potential use as a spin-wave duplexer that allows signal propagation only of selected narrow-band frequencies and duplex transmission in a three-port device comprising a receiver, a transmitter, and their common antenna. The waveguide structure combines three different arms and a circular ring, both made of nanostrip waveguides and a single magnetic material for reliably controllable propagations of spin waves. We attribute the observed duplex transmission of spin waves of narrow pass bands to scattering of spin waves by edge solitons placed at contact areas between the arms and the circular ring. This work proposes the first concept of nano-scale magnonic duplexers operating beyond GHz-frequency ranges.

This paper presents a millimeter-wave tunable hybrid-transformer-based duplexer concept with dual-antenna configuration. By using orthogonal sequentially-rotated linearly-polarized antennas and the hybrid-transformer-based duplexer, the transmitter and receiver duplexes the two antennas with orthogonal circular-polarized signals. An on-chip tuning technique using magnetic coupling is introduced to improve the isolation of the duplexer in case of impedance imbalances. An alternative duplexer with a similar principle using an on-board rat-race coupler is also proposed and designed for comparison. In order to demonstrate the isolation with practical antenna connections, prototypes have been developed to integrate the on-chip duplexer and the rat-race coupler with on-board aperture-coupled microstrip antennas with sequential rotation technique. Measurement results demonstrate the orthogonal circular polarizations for the receiver and transmitter modes on both prototypes. The achieved isolation by the on-chip tunable duplexer is better than 50 dB between 30.2 and 31.2 GHz, while the achieved isolation by the rat-race version is about 20 dB in the same bandwidth.

To obtain Tx-Rx isolation in an in-band full-duplex (IBFD) transceiver, the electrical-balance duplexer (EBD) can be utilized to suppress the self-interference (SI). Although the EBD can provide more than 50 dB cancellation of the SI directly at RF, it cannot fully overcome strong signals reflecting off of nearby objects. As a result, the environmental reflections could still limit the performance of IBFD communication and have to be attenuated in an extra cancellation step, e.g., in digital baseband using a digital SI canceler. While mitigating the reflections is a challenging dimension of this technology, it opens a new opportunity to perform environmental sensing. In this paper, an IBFD transceiver architecture is introduced to enable such context-aware communication functionality. We investigate how the EBD’s SI rejection property influences the performance of the proposed communication device which also functions as a Doppler radar. The simulation result demonstrates that the proposed architecture can produce high-resolution Doppler when the EBD provides > 20 dB Tx-Rx isolation. Concerning the constraints dictated by the application, this paper finally suggests a radar-communication trade-off.

The paper presents an approach that enables trading off the insertion loss versus isolation in the duplexer design. Specifically, the Insertion Loss (IL) of the duplexer filters is reduced by using low-order Bandpass Filters (BPF), while the transmitter (TX) to receiver (RX) isolation is improved using a feed-forward, passive, wideband, cancellation scheme. The proposed cancellation scheme is fully passive and hence the duplexer does not incur power consumption and noise penalties. The linearity of the proposed duplexer is very high limited only by the tunable passive components used in the design. A tunable duplexer prototype is demonstrated with TX-RX isolation better than 50 dB in both TX and RX bands (high band TX: 860–890 MHz, RX: 948–984 MHz; low band TX: 700–718 MHz, RX: 780–801 MHz). Tuning is achieved using digitally controlled switched capacitors with silicon on sapphire (SOS) switches resulting in high linearity.

© 2017 IEEE. A 120GHz in-band full-duplex PMF transceiver with tunable electrical-balance duplexer with on-chip antenna is implemented in a 40nm bulk CMOS technology. The self-interference (SI) cancellation is performed with a fully-differential transformer-based electrical-balance duplexer, resulting in a SI suppression of 30dB over a bandwidth of more than 14GHz. The insertion loss of the duplexer is less than 11dB from TX to fiber and less than 12dB from fiber to RX at a frequency of 120GHz. The balancing network impedance can tolerate load impedances from 45Ω to 93Ω and 38fF to 266fF at 120GHz. For in-band full-duplex operation, the maximum measured data rate is 6.2Gbps. The transceiver with integrated antenna occupies an area of 1.8mm × 1.53mm and has a DC power consumption of 73mW in total. ispartof: pages:103-106 ispartof: Proceedings of the ESSCIRC pages:103-106 ispartof: ESSCIRC location:Leuven date:11 Sep - 14 Sep 2017 status: published

A multi-mode multi-band (MMMB) power amplifier module with integrated duplexer (PAMiD) is developed for mobile handset applications. To reduce size and improve RF performance of Tx front-end, the PAMiD consolidates most of the post-PA networks as well as PA block in a single module. This paper summarizes the RF requirements and challenges addressed in recent years that pursue PAMiD development, and discusses its design consideration.

A Simple radar system consists of following subsystems antenna, duplexer, transmitter, receiver and display unit. The functioning of all these is controlled by radar controller(RC), which is the brain of the radar. This radar controller system is usually a computer which can be used to control these subsystems in different modes as per the requirement presently in Flight Level Radar(FLR), Weapon Locating Radar(WLR) and Troop Level Radar(TLR). The communication protocol required for transmitting information between radar controller and the subsystem is RS-422 differential line to make the communication between the subsystem, cost effective and more efficient LAN protocols can be used. To facilitate the LAN communication Ethernet Media Access Control(MAC) module is needed. The MAC is the portion of the Ethernet core that handles transmission and reception of frames. It performs the frame data encapsulation and de-capsulation, frame transmission and frame reception. An efficient Ethernet MAC is using for display subsystems. FPGA is designed so that the communication between display subsystems and radar controller is through LAN.

This paper presents a transformer-less duplexer based on 2-port N-path bandpass filters (BPFs). The proposed duplexer consists of two quarter-wavelength transmission lines, and an N-path balun BPF which provides an out-of-band (OOB) blocker support for the receiver. A 0.45–0.65 GHz duplexer is implemented in a CMOS 65 nm technology. The duplexer occupies an active area of ≈ 0.7 mm2. In post-layout simulations, the duplexer has > 55 dB of transmitter-to-receiver isolation, < 6 dB of transmitter-to-antenna insertion loss (IL) and < 7 dB of antenna-to-receiver IL.

This paper investigates electrical balance (EB) in hybrid junctions as a method of achieving transmitter-receiver isolation in single antenna full duplex wireless systems. A novel technique for maximizing isolation in EB duplexers is presented, and we show that the maximum achievable isolation is proportional to the variance of the antenna reflection coefficient with respect to frequency. Consequently, antenna characteristics can have a significant detrimental impact on the isolation bandwidth. Simulations that include embedded antenna measurements show a mean isolation of 62 dB over a 20-MHz bandwidth at 1.9 GHz but relatively poor performance at wider bandwidths. Furthermore, the operational environment can have a significant impact on isolation performance. We present a novel method of characterizing radio reflections being returned to a single antenna. Results show as little as 39 dB of attenuation in the radio echo for a highly reflective indoor environment at 1.9 GHz and that the mean isolation of an EB duplexer is reduced by 7 dB in this environment. A full duplex architecture exploiting EB is proposed.

A balanced RF duplexer with low interference in an extremely narrow bandgap is proposed. The Long-Term Evolution band-7 duplexer should be designed to prevent the co-existence problem with the WiFi band, whose fractional bandgap corresponds to only 0.7%. By implementing a hybrid bulk acoustic wave (BAW) structure, the temperature coefficient of frequency (TCF) value of the duplexer is successfully reduced and the suppressed interference for the narrow bandgap is performed. To achieve an RF duplexer with balanced Rx output topology, we also propose a novel balanced BAW Rx topology and RF circuit block. The novel balanced Rx filter is designed with both lattice- and ladder-type configurations to ensure excellent attenuation. The RF circuit block, which is located between the antenna and the Rx filter, is developed to simultaneously function as a balance-tounbalance transformer and a phase shift network. The size of the fabricated duplexer is as small as . The maximum insertion loss of the duplexer is as low as 2.4 dB in the Tx band, and the minimum attenuation in the WiFi band is as high as 36.8 dB. The TCF value is considerably lowered to .

A full-duplex transceiver for wireless inter-chip data communication in an engine controller board of hybrid electric vehicles is demonstrated. The amplitude shift keying (ASK) transceiver incorporates a clock data recovery circuit for crystalless operation as well as for simultaneous generation of a 24-GHz local oscillator signal and a 400-MHz clock for data recovery. The transceiver also integrates an on-chip antenna and a duplexer. The bit error rate (BER) degradation of RX due to the full duplex operation of transceiver with an on-chip antenna is negligible when the input power is greater than -44 dBm necessary to achieve a BER of less than 10-12. This is the first demonstration of full duplex operation for an integrated circuit incorporating an on-chip antenna. The transceiver is fabricated in a 130-nm CMOS technology and consumes 245 mW.

In radar measurements the observed area is limited by the antenna beamwidth and due to the usually ���xed transceiver position, only unhidden targets in a small observation area can be detected. Furthermore, bulky lens dimensions prevent the use of radar systems in constricted surroundings despite the small dimensions of microwave monolithic integrated circuit (MMIC) radars. To avoid this issue, a new system concept for a ���exible and low cost 160 GHz radar sniffer probe is presented. The ���exible sniffer probe is an extremely low loss dielectric waveguide with a dielectric elliptical lens (28 dBi) at the end. The dielectric waveguide has dielectric losses of 4.5 dB/m at 160 GHz and high ���exibility, supporting bending radii of 1.5 cm with negligible losses. To feed the dielectric waveguide a metallic waveguide with a duplexer is used which is fed by a special MMIC-to-metallic waveguide transition. The proposed system expands the known radar measurement scenarios with new industrial, medical, and security applications., acceptedVersion

The ability to achieve ubiquitous connectivity and run powerful ‘Apps’ on today's Smart phones requires a front-end radio able to handle tremendous data rates; and that, requires access to the full bandwidth owned by service providers. Once, the front-end radio consisted of a single power amplifier (PA), filter/duplexer, a switch and a low noise amplifier (LNA). Early on, a cell phone might be able to access 2 or 3 frequency bands. Today, the iPhone 7 accesses 23 to 24 GSM, CDMA and LTE frequency bands, while the Galaxy flag ship phones from Samsung have 16 bands (not counting the GPS, Wi-Fi, Bluetooth and NFC radios). Power amplifier, Low noise amplifier and switch functions can be combined-important for cost and size — but, proliferation of usable bands has driven up filter count. New bands are being created (opening up more frequency spectrum) and more challenging; existing bands are now being combined in what is called Carrier Aggregation. This requires better performance from the filter and also drives filters to become smaller as handset manufacturers struggle to add more filters into a limited space. This has created (in just a few years) a whole new billion dollar industry focused on building high quality ultra-miniature filters; An industry where better quality filters enable better wireless communication, which-in turn-drives the technology to build better filters.

Practical implementation of monolithic hybrid transformer duplexers have been limited by the poor common-mode isolation. In this paper, a differential hybrid transformer duplexer that covers 3GPP bands I, II, III, and IX between 1.7 and 2.2 GHz is introduced. It achieves a differential to differential isolation of 60 dB in the transmit (TX) band and 40 dB in the receive (RX) band, and a differential to common-mode isolation of 60 dB in both bands. The duplexer with a cascaded low-noise amplifier (LNA) achieves a noise figure of 5.6 dB in the RX path and an insertion loss of 3.7 dB in the TX path. The duplexer and LNA are implemented in a 90-nm CMOS process, consume 20 mA, and occupy an active area of 0.6 mm2.