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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).

A new ultra-wideband millimetre-wave passive balanced duplexer (DUX), employing a lumped-element Wilkinson power divider and grounded-centre-tap transformer, has been developed using 0.18- μ m BiCMOS process for fifth generation operations at 28, 37, 39 GHz, and beyond. The developed DUX is configured single-ended transmitter (TX) and antenna (ANT) ports and differential receiver (RX) port. It has an inherent matching at TX, RX and ANT ports, high TX–RX isolation, and highly balanced differential RX waveforms, and is ready for direct integration with a differential low-noise amplifier. Analysis has been performed to confirm the DUX's characteristics and assess its performance. Measured isolation from TX to each single-ended RX port is higher than 50 and 40 dB from dc-20 GHz and dc-60 GHz, respectively. Measured insertion loss from TX to antenna is better than 6.3 dB across 13–53 GHz. Measured insertion loss from ANT to differential RX port is lower than 13.8 dB from 25 to 57 GHz with 10.8 dB at 40 GHz. The core chip only occupies 0.3 mm2.

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.

The duplexer is a key device for simultaneous signal transmission and reception, and a lot of duplexers based on frequency division principle have been proposed. However, there are some defects of duplexers based on frequency division such as interference between the transmitting and the receiving signals. Development of dual-polarization transmit and receive module offers a significant way to solve the above problems. However, limited by the processing accuracy and other issues, there are very few orthomode polarization duplexers designed for the terahertz frequency band. In this article, a novel duplexer in THz band is proposed. The structure of the duplexer proposed in this paper is very simple, easy to process in the terahertz frequency band, and has very good realizability. The simulation results of the duplexer show that the insertion loss of both two modes is less than 0.2 dBm, the return loss is better than 20 dBm, and the isolation of two orthomodes is better than 68 dBm.

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.

In this paper, a novel triplexer using the substrate-integrated suspended line technology is proposed. Two matching circuits are designed to connect the three filter channels for the triplexer construction. The used bandpass filters are composed of a low-pass filter and a high-pass filter, and they have advantages of high controllability and low insertion loss. For the proposed triplexer, two adjacent filter channels compose a duplexer. Based on the design consideration, the triplexer can be extended to a multiplexer. The proposed design is further improved by using a patterned suspended substrate for loss reduction. The triplexer achieves good isolations among the three ports and low insertion losses of 1.4/1.3/0.8 dB for the three channels of 0.8, 2.5, and 5.8 GHz, respectively.

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.

This thesis explores a new range of electromagnetic structures made available by a subtle change in the interpretation of how resonators interact. The focus is on microwave filters and antennas that are essential to wireless communication. The standard interpretation is that filters and antennas are made from a series of intercoupled resonators, with multiple paths through the structure allowing transmission zeros that increase selectivity and isolation between ports. This thesis instead begins with the assumption that the resonators of multi-mode structures are more effectively interpreted as not interconnected at all, being perfectly orthogonal to each other. The resonators are now equivalent to the structure’s eigenmodes and couple only to the ports, in parallel, with the phase and amplitude relationships of these parallel external couplings allowing a generalised frequency response with maximum transmission zero flexibility. This thesis aims to improve the size, cost and performance of filters and antennas using parallel-coupled multi-mode resonating structures by contributing six novel implementations.The first contribution introduces a bandpass filter made from a parallel coupled, triple-mode, silver-plated, surface-mounted ceramic cube, with a novel coupling topology featuring over-coupled single-mode input/output quarter wave stripline resonators. A single cube achieves class leading ratio of quality factor to volume (Q/V), three flexibly placed transmission zeros and allows a simple cubic construction without the need for chamfers for inter-resonator coupling. To validate the proposed design and analysis method, multiple filters are designed and simulated. Moreover, two DCS-1800 Band-3 (utilized in mobile communications) single cube transmit filters are fabricated and measured.The second contribution is a duplexing filter with high isolation. The device is based on triple mode filters that are built using silver plated ceramic cubes. To create a six-pole, six-transmission zero filter in the DCS-1800 band, two cubes are cascaded. To improve spurious harmonics, low dielectric caps are placed on the cube faces. These caps push the first cube spurious up in frequency by around 340 MHz compared to the uncapped cuboid, allowing a 700 MHz spurious free window. To verify the design, a DCS-1800 duplexer with 75 MHz wide bands is built. It achieves around 1 dB of insertion loss for both the receive (Rx) and transmit (Tx) ports with around 70 dB of mutual isolation within only 20 MHz band separation, using a volume of only 30 cm3. It is estimated that a similarly specified coaxial cavity duplexer would need a volume of at least 300 cm3.The third contribution is a triple-mode silver-plated ceramic cavity bandpass filter with wide spurious-free response. It uses single mode ceramic slabs as interfacing resonators with the triple-mode cube to give wide spurious-free performance up to 4 GHz for an 1800 MHz base-station filter. Three square apertures at the slab-cube interface give simple and flexible control of transmission zero placement while maintaining low insertion loss. The parallel nature of the slab-to-cube coupling allows a simple cubic structure without chamfers or inter-mode coupling elements. A seven-pole filter in the DCS-1800 transmit band using a slab-slab-cube-slab-slab structure is built and measured. The filter achieves 1 dB of band edge insertion loss with more than 50 dB of attenuation, 20 MHz from the band edges, from an 11 cm3 package. The wideband response shows more than 40 dB of attenuation up to the frequency 3.7 GHz.The fourth contribution is a triple-mode band-stop ceramic cavity filter utilizing parallel-coupled resonators. A transmission line, etched onto the face of a silver-plated ceramic cube, couples to three modes in parallel, avoiding any inter-resonator coupling perturbations. By varying only a few structural parameters, the coupling strengths into each mode can be controlled, and highly flexible band-stop filtering functions are demonstrated. A 30 MHz band-stop filter at 1800 MHz, from a roughly 27 mm3 ceramic block mounted to a copper base, is fabricated and measured. It achieves 26 dB of attenuation, with less than 0.3 dB of insertion loss 20 MHz away from the stop-band, and less than 0.3 dB of reflection loss in the stop-band, closely matching the simulation.The fifth contribution demonstrates a generalised frequency response for cavity filters from six modes coupled in parallel. The six modes belong to two parallel-coupled triple-mode spheres and are coupled in parallel via two half-wavelength transmission line resonators. The theory of phase and amplitude control of parallel couplings into spherical cavities is introduced by way of coupled resonator models, and the structure of two combined spheres is detailed. The theory and simulations prove that multiple transmission zeros can be arbitrarily placed, including inside the passband to create multiple bands and beyond infinity (imaginary frequencies) for flattened group delay. Several design examples of two spheres in parallel are presented to demonstrate a high degree of flexibility of transmission zero placement, and one example is fabricated and successfully tested.The sixth contribution reinterprets the assumption that mutual coupling is the mechanism that leads to the degradation of isolation between the active ports of antenna arrays. It is shown that a coupled-resonator model with series-coupled mutual coupling breaks down when applied to multi-mode/multi-port antenna arrays and limits the achievable isolation. An improved model based on parallel-coupled modes is presented. This model suggests that poor isolation is more accurately caused by unbalanced antenna modes. Using this model, several novel examples of simple and compact dual- and triple-mode antennas show how to maximize isolation in multi-mode antennas by balancing the modes’ resonant frequencies and radiation bandwidths. For comparison, the mutually coupled assumption limits isolation to around 20 dB in the proposed novel structures whereas 40 to 70 dB is possible when parallel-coupled modes are considered. Based on the developed concept, a compact triple-mode two-pole-filtering antenna is fabricated at 3500 MHz with 160 MHz of bandwidth and more than 40 dB of isolation between the antenna ports.

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.

Directional coupler is a passive microwave device which is actively used in most of the microwave circuits such as modulator, antenna feeder network, duplexer etc. and needs a special attention towards the design philosophy as well as optimization of various key parameters critically in order to improve their performance for large verity of applications. This article is focused about the basic design concept of single section and multi-section directional coupler using complex mathematical equations, simulation using formulated results and optimization of various influencing parameter of coupler such as coupling factor, bandwidth, substrate permittivity, branch impedance etc. which results into determination of key performance indicators of a coupler such as insertion loss, return loss etc. in order to optimize the directional coupler for required application.

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.

In this paper, a bridge duplexer is designed, which can integrate and output signals with similar frequencies. It consists of two band-pass filters, two 3dB power couplers and a part of transition structure. The whole system works in Ku frequency band and the two input ports respectively input narrowband signals and broadband signals. The overall simulation results show that the return loss of narrow-band and wide-band signal input ports is greater than 17dB and 20dB respectively, the insertion loss is less than 0.2dB and 0.3dB respectively, and the isolation between the two input ports is higher than 25dB, which indicates that the design can well meet the actual engineering requirements.

This work studies transmit (TX) and receive (RX) power losses in single antenna in-band full duplex transceiver architectures employing passive self-interference cancellation (SIC) filters. Three different RF front-end (RFFE) approaches to realize passive primary TX-RX isolation - a circulator, an electrical-balanced duplexer (EBD), and quadrature balanced power amplifiers (QBPA), are considered and analyzed. The analysis assumes the SIC stage is implemented as a dual delay-line FIR filter with adjustable delay and amplitude. Closed-form expressions are derived to describe the accuracy of this filter in approximating frequency-selective channels over a wide bandwidth. System-level simulations at the frequency range between 5 and 6 GHz demonstrate that all three RFFEs can provide more than 60 dB isolation over 80 MHz of bandwidth for antenna reflections as high as 14 dB. TX and RX losses vary depending on the RFFE architecture and the insertion loss of the FIR filter.

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 microwave duplexer with high isolation is presented in this paper. The device is based on triple-mode filters that are built using silver-plated ceramic cuboids. To create a six-pole, six-transmission-zero filter in the DCS-1800 band, which is utilized in mobile communications, two cuboids are cascaded. To shift spurious harmonics, low dielectric caps are placed on the cuboid faces. These caps push the first cuboid spurious up in frequency by around 340 MHz compared to the uncapped cuboid, allowing a 700-MHz spurious free window. To verify the design, a DCS-1800 duplexer with 75-MHz widebands is built. It achieves around 1 dB of insertion loss for both the receive and transmit ports with around 70 dB of mutual isolation within only 20-MHz band separation, using a volume of only 30 cm3 .

Electrical balance-based full-duplex front-end allows high power operation but has strong tradeoff between Tx and Rx insertion loss. In this paper, we present a capacitive bridge-based duplexer for full-duplex operation with tunable Tx/Rx insertion loss to improve link budget in an asymmetric data network. Theoretical analysis is done to show that capacitive bridge-based duplexer can be better than hybrid transformer in CMOS process. Capacitive bridge architecture is suitable for insertion loss tunability and this tunability gives an additional advantage of increasing the range of allowed antenna impedance for the given balance network. The fully integrated duplexer with receiver is implemented in a 130-nm CMOS process, and is capable of handling Tx power of upto +16dBm at antenna. The prototype chip demonstrates tunable Tx/Rx insertion loss achieving an overall receiver noise figure of 5.7–7.5dB and a Tx insertion loss of 3.9–5.6dB. Self-interference cancellation of >50dB is measured for 20-MHz RF bandwidth in 2.4–2.6-GHz frequency range.

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.

In frequency division duplex systems, spurious emission from transmitter (TX) can fall into receive band and lead to significant receiver desensitization. In this paper, a DSP-based solution that relies on a linear auxiliary receiver to cancel receive band noise (RxBN) from the received signal is demonstrated. This technique allows reduction of duplexer rejection requirements in the receiver band, and associated reduction of insertion loss in the TX band, thus resulting in high-power amplifier (PA) efficiency and small duplexer footprint. The PA architectures that inherently have high RxBN (such as envelope tracking and the digitally modulated PAs) can substantially benefit from this technique. Experimental results based on off-the-shelf system implementation are demonstrated using a digital PA, and more than 22 dB cancellation is achieved to reduce RxBN below thermal noise floor at 836 MHz with 45 MHz duplex spacing.

A highly linear receiver (RX) front end with integrated hybrid transformer (HT) for frequency-division duplexing mobile communications is reported. The HT, implemented with a three-winding coplanar transformer, is used to interface the RX front end with the antenna and the power amplifier. The primary is driven at its center tap with the transmitted signal and at one input with the antenna signal, while the other input is connected to an on-chip programmable balancing impedance. The two secondary drives a differential push–pull common-gate low-noise amplifier (LNA). Assuming a perfectly linear hybrid only 45 dB of transmitter (TX)–RX isolation and 35 dB of common-mode rejection are required to meet the intermodulation specs thanks to the +25-dBm receiver IIP3. This would drastically simplify hybrid balancing and adaptation loop. Cascaded noise figure of duplexer, LNA, and baseband is below 6.7 dB and TX insertion loss below 4.3 dB from 1.7 to 2.1 GHz. The implemented prototype in 28-nm CMOS has an active area of 0.7 mm2 and requires only 26 mW.

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.

In this paper, two architectures for tunable duplexers are presented. The tuning is accomplished through variable capacitance and resistance. The architectures are based on a three element series-parallel resonator, with one pass and one stop frequency. Both architectures rely on filtering as well as cancellation for good Tx to Rx isolation while maintaining low insertion loss. The first architecture, the filtered transformer balanced (FTB) isolator, has single ended transmit and antenna ports and a differential receive port. The second architecture, the cross coupled filtering (CCF) isolator, is fully differential. For a resonator $Q$ of 50, the impedance ratio of the resonator at pass and stop frequencies is 18.5 dB for 3GPP band-I. In the FTB isolator, this results in 1.65-dB Tx and 2.14-dB Rx insertion loss, and 53 dB isolation for a 20-MHz channel bandwidth. In the CCF isolator, this results in 1.9-dB Tx and 1.9-dB Rx insertion loss, and 59-dB isolation for a 20-MHz channel bandwidth. These figures are obtained with a 20% resistive mismatch, showing feasibility of good performance in an environment with changing impedance. As the operating frequencies of cellular systems increase, these structures will become fully integratable due to the reduced sizes of inductors and transformers.

This paper presents the design consideration on a converged Rx surface acoustic wave (SAW) duplexer module for integrated RF front end. Two different matching-circuit and notch-circuit configurations were examined with importance placed on electrical characteristics (insertion loss and isolation of duplexer) and simplification of module, respectively. From circuit simulations and examinations, we verified that a simplified design was best in terms of both characteristics and space in the case of a finite inductor’s Q. We also fabricate a quad-band converged Rx module (Band I + II, V + VIII) using an SAW duplexer and verified that its electrical characteristics agree well with our simulation results.

To develop the high-performance filters and duplexers required for recent long-term evolution frequency bands in mobile handsets, a surface acoustic wave (SAW) resonator is needed that has a higher quality (Q) and a lower temperature coefficient of frequency (TCF). To achieve this, the authors focused on acoustic energy confinement in the depth direction for a rotated Y-X LiTaO3 (LT) substrate. Characteristics of multilayered substrates with low-impedance and high-impedance layers under LT layer were studied numerically in terms of acoustic energy distribution, phase velocity, coupling coefficient, and temperature characteristics employing a finite-element method simulation. After several calculations, a novel multilayered structure was developed that uses SiO2 for a low-impedance layer and AlN for a high-impedance layer under the thin LT layer. A one-port resonator using the new substrate was fabricated, and its experimental results showed that the developed resonator had a Bode-Q over 4000 and TCF of −8 ppm/°C, which are four times higher than and one-fifth as small as those of a conventional 4° YX-LT SAW resonator, respectively. By applying this technology, a band 25 duplexer with very narrow duplex gap was successfully developed, which shows extremely low insertion loss, steep cutoff characteristics, and stable temperature characteristics.

A hybrid transformer-based CMOS tunable duplexer with a single-ended blocker-tolerant low-noise amplifier (LNA) is proposed for a highly integrated reconfigurable RF front-end architecture. The proposed LNA adopts $Q$ -enhanced $LC$ notch filter at the source of the cascode device and $LC$ bandpass filter at the load. It improves the blocker tolerance and linearity of the receiver by rejecting unwanted out-of-band blockers and transmitter (TX) leakage signals. The duplexer with the notch-filtered LNA was fabricated in a 65-nm CMOS process. It has a voltage gain of 24.2 dB from the antenna to the LNA output with 28-dB notch filtering, cascaded noise figure of 6.4 dB, TX insertion loss of 3.8 dB, and IIP3FD of 52.4 dBm. It can also cover a mid-band range from 1.6 to 2.2 GHz in cellular applications. It draws an average current of 8 mA from a supply voltage of 1.2 V and has an active area of 1.19 mm2.

Relentless pressure to reduce the size of filters, duplexers and multiplexers in mobile phone RF front end modules requires close packing of the filters and any associated PCB or SMT inductors. In these multiplexers, however, every Tx filter has to reject every Rx frequency and vice versa, while TDD bands/filters must be rejected by and reject nearly every other band -60 dB typical with -55 dB guaranteed. These seemingly contradictory requirements can both be satisfied if we reduce the magnitude of the grounding inductors of the filters to a point that their mutual inductance is not significantly degrading isolation. The Band 25 duplexer described is 1.5 mm x 1.1 mm x 0.6 mm.

Discrepancia entre la información que aparece en el artículo que indica que el copyright es de Elsevier, y la información que aparece en la página de la revista y en el Copyright Clearance Center que indican © 2019 The Authors. Published by Elsevier B.V., así como que el artículo está publicado en Open Access under a Creative Commons licence, This work presents the design and experimental validation of a high performance, compact, waveguide duplexer operating from 91.5 to 96.5 GHz for its integration in diverse W-band microwave equipment as in plasma diagnosis applications. It uses a single frequency band, with two signals discriminated by different orthogonal circular polarization, which is generated by means of a septum orthomode transducer (OMT) polarizer. Moreover, this component is optimized loaded with the horn antenna for improving the overall system performance. It is explained how these two components are integrated into a very compact duplexer, designed using efficient numerical algorithms. The manufacturing process by mean of high precision milling, and including electrical discharge machining (EDM) has led to excellent performances. The measured return loss level and isolation are higher than 30 dB, and the insertion loss level is below 0.3 dB. Finally, the key parameter in this device, which reflects the symmetry in the manufacturing process, i.e., the axial ratio, is lower than 0.6 dB for both polarizations, an excellent result showing the potential of the presented design, This work was supported by the Spanish government under grants (ADDMATE) TEC2016-76070-C3-1/2-R (Agencia Estatal de Investigación, Spain, Fondo Europeo de Desarrollo Regional: AEI/FEDER/UE) and the program of Comunidad de Madrid, Spain S2013/ICE-3000 (SPADERADARCM)

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

A tunable integrated electrical balanced duplexer (EBD) is presented as a compact alternative to multiple bulky surface acoustic wave (SAW) and bulk acoustic wave (BAW) duplexers in third-generation (3G)/fourth-generation (4G) cellular transceivers. A balancing network creates a replica of the transmitter (TX) signal for cancellation at the input of a single-ended low-noise amplifier (LNA) to isolate the receive path from the TX. The proposed passive EBD is based on a cross-connected transformer topology without the need of any extra baluns at the antenna side. The balancing network enables a single-ended LNA with reliable high TX power operation up to 22 dBm by alleviating the common-mode coupling. The duplexer achieves around 50-dB transmitter–receiver (TX-RX) isolation within a 1.6–2.2-GHz range. The cascaded noise figure (NF) of the duplexer and LNA is 6.5 dB, and TX insertion loss (TXIL) of the duplexer is about 3.2 dB. The duplexer and LNA are implemented in a ${\hbox{0.18-}}\mu{\hbox{m}}$ CMOS process and occupy an active area of ${\hbox{0.35 mm}}^{2}$ .

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.

In order to cope with the worldwide shortage of the MLCC (multilayer ceramic capacitor), this paper proposes a methodology of integrated lattice balun using a high permittivity substrate material. It is well known that discrete radio frequency (RF) front-end circuits are composed of MLCCs and chip inductors in many electronic products. Inserting a high permittivity material to replace decoupling capacitors is an effective method. Another way to lessen the quantity of MLCCs is embedding an integrated RF front-end circuit instead of MLCCs, such as a balun, filter or duplexer. In this study, an integrated lattice balun was designed for DCS (digital cellular system) 1800 MHz. The simulation results show that the designed balun achieves a return loss $< -23$ dB, an insertion loss $\gt -0.25$ dB, a phase deviation form $180 \circ$ to $182 \circ$ and a magnitude deviation of less than 1.1 dB in the frequency range of DSC.

CMOS circulators/duplexers based on nonreciprocal transmission line (TL) are proposed for full-duplex transceiver front ends operating at 100 GHz band. Offering nonreciprocal propagation at millimeter wave regime, the presented nonreciprocal TL is made of two parametric mixing stages modulated by signals at around 1/6 of the RF frequencies. Operating together with integrated hybrid couplers, circulators or duplexers can be implemented for full-duplex communication. Realized in CMOS process, this nonreciprocal TL achieves over 45 dB isolation throughout its isolation bandwidth of 1.5 GHz, a maximum 9.5 dB insertion loss (IL) and an over 10 dB return loss.

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

Band 28 has wide bandwidth of 45MHz and narrow duplex gap of 10MHz in 700MHz band, and since digital terrestrial TV channels in some countries are overlapped with lower frequency range of the uplink band, two types of duplexer which have slightly shifted passbands need to be used. This paper describes a novel switchable SAW duplexer which can cover both bands in one duplexer. By using a filter design technique with unique switching circuit, and wideband and low temperature drift SAW resonator technology, high performance such as 2.6/3.0dB insertion loss and 55dB isolation have been achieved, in addition to more than 13/16dB near point attenuation only 5/8MHz apart from the passband edge. The developed switchable duplexer can lead the reduction of 40% in mounting area on RF front-end circuit of mobile terminals.

This Paper presents the design of interdigital filters for the application of duplexer. The Design is Based on the coupling between the micro strip resonators of Quarter Wavelength Long. The designed filters are of seventh order Chebyshev type with a passband ripple of 0.2dB and FBWs of 6.2% and 5.7%. The structure is simulated in the electromagnetic simulation tool such as ADS. The results achieved are of insertion loss S(2,1) around 2dB, Return Loss S(1,1) is of around 17dB and the stop band attenuation of 30dB. The Alumina substrate with an height of 1.27mm and Dielectric Constant of 9.8 is used to reduce the size of the filters. The Designed filters can be used for the Development of Duplexer by increasing the Stopband attenuation to more than 50dB.

A 0.7–1GHz tunable front-end module (FEM) is presented for frequency-division duplexing and in-band full-duplex. It combines an electrical-balance duplexer (EBD) and tunable surface-acoustic wave resonators, demonstrating for the first time that these techniques are compatible and can be tuned independently. The EBD is integrated with a low-noise amplifier (LNA) in 0.18μm SOI CMOS and can operate with any antenna with a VSWR less than 2.3:1. The tunable FEM achieves more than 50dB dual-frequency isolation prior to the LNA, 2.6–3.4dB TX insertion loss and +58/+42dBm TX/RX-path out-of-band-IIP 3 , respectively. It has

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.

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 .

Design and implementation of a low-loss K-band duplexer consisting of two narrow bandpass filters with low-impedance open-loop resonators (OLRs) is presented. Narrow bandpass filters of 4%-7% bandwidth were often implemented with OLRs, but previous designs used OLRs mostly with 50 Ω linewidth. The design process was complicated due to multiple coupling mechanisms and multiple spurious response frequencies, often resulting in excessive insertion loss, especially at higher center frequencies. With the proposed design procedure for OLR filters, the values of the low-impedance line (less than 50 Ω) and proper coupling spacing are determined in the process of optimizing the filter performance, resulting in low insertion loss up to above K-band frequencies. The size of the proposed filter is also reduced to 64% of the conventional OLR filters. As an example of the proposed design method, a duplexer consisting of 4% narrow bandpass filters centered at 18.7 GHz and 22.5 GHz was implemented and measured, and the maximum insertion loss in each passband was 1.2 dB, which is much less than those of the previous design approaches.

In this paper, we present the modeling and experimental validation of an efficient, compact, and high-isolation waveguide duplexer operating at 225 GHz. While duplexers based on ferrite circulators are key components of many monostatic radar systems, at W-band frequencies and above the performance of waveguide circulators rapidly deteriorates. The design presented here uses a ferrite-free duplexing concept based on transmitting and receiving in orthogonal circular polarizations. The circular polarization is efficiently generated in waveguide using a septum orthomode transducer polarizer, leading to a compact device with a single horn antenna. The complete duplexer is designed using efficient numerical algorithms, resulting in a fabricated device with a measured 10% fractional bandwidth, a return loss better than 20 dB, isolation of 30 dB, and insertion loss below 1 dB.

This paper presents a novel high performance W-band MEMS duplexer for digital signal transceiver applications. The design of duplexer filters follows the insertion loss method with a Chebyshev polynomial to meet the desired spectral responses. The insertion loss and return loss of the optimized duplexer are -0.3dB and -18dB respectively, while the isolation between two pass bands is -55dB. A micro-fabrication process is designed based on MEMS technology. The deep reactive ion etching (DRIE) is used for high-aspect-ratio filter cavity mold structure. Micro-electroforming, plastic embossing, and electroplating techniques are used for low-cost and high-precision mass production program for the duplexer. Fabrication error tolerance is analyzed and it is reasonable to control the shift of frequency and return loss in the range of 0.05GHz and 2dB respectively with the designed fabrication process based on MEMS technology. It proves that the proposed micromachining fabrication technique is suitable for high performance W-band waveguide filter and duplexer design in terms of stability of RF performance.