Tunable Matching Network Research Articles

Unimodal criteria of tunable matching network

A set of unimodal criteria for a tunable matching network is presented to make the objective function of the matching network to be unimodal, which leads to the finding of the global optimum point. Furthermore, the proposed unimodal criteria are extended to the lossy matching network.

Binary search algorithm for adaptive impedance matching network

A novel design strategy for adaptive impedance matching network which consists of two tunable components is presented. The input resistance is controlled by the first tunable component and independent of the second tunable component. Additionally, the proposed strategies ensure that the input resistance is proportional to the first tunable component and input reactance is proportional to the second tunable component. Therefore, the binary search algorithm is employed to calibrate the tunable matching network. In contrast to the single-step method, the convergence speed is improved from O(N) to O(log N).

Polarization Reconfigurable Broadband Rectenna With Tunable Matching Network for Microwave Power Transmission

A broadband polarization reconfigurable rectenna is proposed, which can operate in three polarization modes. The receiving antenna of the rectenna is a polarization reconfigurable planar monopole antenna. By installing switches on the feeding network, the antenna can switch to receive electromagnetic (EM) waves with different polarizations, including linear polarization (LP), right-hand and left-hand circular polarizations (RHCP/LHCP). To achieve stable conversion efficiency of the rectenna ( $\eta_{r}$ ) in all the modes within a wide frequency band, a tunable matching network is inserted between the rectifying circuit and the antenna. The measured $\eta_{r}$ changes from 23.8% to 31.9% in the LP mode within 5.1–5.8 GHz and from 22.7% to 24.5% in the CP modes over 5.8–6 GHz. Compared to rectennas with conventional broadband matching network, the proposed rectenna exhibits more stable conversion efficiency.

A SiGe BiCMOS Power Amplifier Using a Lumped Element-Based Impedance Tuner

A dual-path multi-band power amplifier (PA) with a tunable output matching network is presented for long-term- evolution (LTE) handset applications. To optimize output load impedances for various power regions with various frequency bands, an impedance tuner implemented using lumped elements is used. The dual-path multi-band PA fabricated using $0.35{\mathchar702D}\mu{\rm m}$ SiGe BiCMOS process is evaluated for the evolved UMTS terrestrial radio access (E-UTRA) bands 1, 2, 3, 5, and 8 with a 10 MHz bandwidth (BW) LTE 16 quadrature amplitude modulation signal having a peak-to-average ratio of 6.4 dB.

MoS2 thin films as electrically tunable materials for microwave applications

In this paper, we show that a MoS2 thin film formed from a mixture of pristine MoS2 monolayers and few-layer flakes deposited on a coplanar waveguide (CPW) is acting as an electrically tunable microwave material. In this respect, we have seen that up to 30 GHz, the transmission and reflection parameters of the CPW depend on the applied voltage. We have extracted from the measurements an equivalent circuit and have observed that the surface resistance is dependent on the DC applied voltage, as in the case of other two-dimensional materials such as graphene. So, the device is acting as a tunable matching network via an applied DC voltage.

Active inductor-based tunable impedance matching network for RF power amplifier application

This paper presents the use of a new structure of active inductor named cascoded flipped-active inductor (CASFAI) in a T-type high-pass tunable output matching network of a class-E RF power amplifier (RFPA) to control the output power and enhance the efficiency. The designed CASFAI behaves as an inductor in the frequency range of 0–6.9GHz, and has reached to a maximum quality factor of 4406, inductance value of 7.56nH, 3rd order harmonic distortion better than −30dB for 0dBm input power, while consumes only 2mW power. In order to consider the performance of the proposed active inductor-based tunable output matching network on the output power level and power added efficiency (PAE) of RFPA, the CASFAI is applied as a variable inductor to the output matching network of RFPA. The overall circuit is designed and validated in ADS in a 0.18µm CMOS process and 1.5V supply voltage. The results indicate that by increasing the inductance value of the matching network in constant operating frequency, the PAE peak moves from high power to low power levels without any degradation. Therefore, it is possible to maintain the power efficiency at the same maximum level for lower input drive levels.

Impact of time misalignment and input signal statistics in dynamically load-modulated amplifiers

The effect of time misalignment between the radiofrequency (RF) input and tunable matching network control signal in dynamically load-modulated power amplifiers (Pas) is investigated in theory and practice. Moreover, the impact of different input signal statistics is considered. A simple amplifier model is used for the study, based on which the impact on output power, efficiency, and linearity is explored with various generic multi-tone signals. Furthermore, to experimentally verify the results, a 10 W dynamically load-modulated RF PA is measured. As expected, proper synchronization of the signals is crucial, especially as channel bandwidth increases. Additionally, it is shown that the input signal characteristics, such as the amplitude distribution, are important. Moreover, the prototype RF PA is measured with a 1.4 MHz long-term evolution (LTE) signal delivering an average output power of 33.9 dBm with 46% efficiency. Finally, high efficiency and linearity is maintained over output power by scaling the drain supply voltage.

A Novel Load Mismatch Detection and Correction Technique for 3G/4G Load Insensitive Power Amplifier Application

This paper proposes a novel load mismatch detection and correction technique to develop a load insensitive power amplifier (PA). The presented algorithm for the technique can simply be implemented by handling load impedance as a region rather than a point. Based on the detection results, a tunable output matching network (TOMN) corrects a mismatched load and transforms it into a desired region, thereby dramatically enhancing PA performances under load mismatched condition with a minimal compromising at a matched load. The detectors and TOMN were simply implemented using a 0.18-μm silicon-on-insulator field-effect transistor, which were integrated with a 2-μm InGaP/GaAs HBT PA monolithic microwave integrated circuit into a single module. A PA module was implemented using more advanced impedance detectors having eight-phase regions, which was measured with WCDMA R'99 and 10-MHz 16QAM long-term evolution signals centered at 1.95 GHz for verification of the proposed idea. When compared to a conventional PA, excellent adjacent channel leakage ratio improvements of 12.7 and 8.3 dB, respectively, were achieved under output voltage standing-wave ratio (VSWR) of 2.5:1 for both applications. Moreover, the idea was extended for efficiency enhancement in a linearity spec-compliant impedance region, and the PA showed power-added efficiency improvements of 1.6% and 0.5%, respectively, under output VSWR of 2.5:1 for both applications.

General expression for tunable matching network efficiency in the case of complex impedances

ABSTRACTThe design of matching networks is generally based on lossless devices, hence rendering difficult to anticipate their performance when both impedances are complex. To be more predictive in terms of insertion loss and matching impedance coverage, a rigorous method is proposed for the first time to calculate the efficiency of a tunable matching network based on the quality factor of its components, with source and load complex impedances. The method allows optimizing the topology of the matching network, depending on the location of the source and loading impedances in the Smith chart. It is the first time to our knowledge that a complete analytical formulas is given to predict the matching network's efficiency in function of available components quality factors in the case of source and load complex impedance. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1160–1166, 2014

Fully Monolithic BiCMOS Reconfigurable Power Amplifier for Multi-Mode and Multi-Band Applications

A power amplifier (PA) supporting wideband code division multiple access, long-term evolution (LTE), and wireless local area network applications has been implemented in 0.18- $\mu{\hbox{m}}$ SiGe BiCMOS technology. The PA integrates a tunable input matching network, a broadband output matching network, and adaptive bias circuits in a single chip to achieve high linearity and high power in different modulation schemes and operating bands. The three-stage PA adopts a differential-type configuration without using through-silicon-via technology to deliver 4 1.3–42 dB of gain and 28.2–28.6 dBm of 1-dB compression output power with a 20.8–27.6% power-added efficiency (PAE) at 1.85–2.5 GHz. To further validate the usefulness of the proposed PA, the envelope-tracking PA is designed to improve the PAE by 6.5% within the linearity specification of a 24.7-dBm average output power and a $-$ 33-dBc adjacent channel leakage ratio for 2.35-GHz 16 quadrature-amplitude-modulation time-division LTE signal with 20-MHz bandwidth.

CPW-Fed Frequency-Reconfigurable Slot-Loop Antenna With a Tunable Matching Network Based on Ferroelectric Varactors

A frequency-reconfigurable slot-loop antenna with a tunable matching network (TMN) is designed, fabricated, and measured. The frequency-reconfigurable antenna is designed by loading ferroelectric (FE) varactors along a slot loop. The varactor-loaded slot-loop antenna is fed using a coplanar waveguide (CPW) line rather than a microstrip line to preserve the advantage of being uniplanar. However, because it is more difficult to achieve a good matching over wide bandwidth with a direct CPW feed, we propose to add a TMN. It is found that the TMN can be realized using a series varactor, which does not increase the size of the antenna. Measurement results show that by adjusting the bias of the FE varactors from 0 to 15 V, the operating frequency of the antenna can be tuned from 6.71 to 9.14 GHz, translating into a 30.6% frequency tuning range (FTR). At 6.71 GHz, the size of the slot loop is $0.056 {\lambda _0} \times 0.056{\lambda _0}$ . When biased at 15 V, the antenna gain is $ - $ 3.1 dBi. Over the entire FTR, the return loss is greater than 20 dB, demonstrating the effectiveness of the tunable matching technique.

자동 변환 임피던스 매칭 네트워크를 갖는 CMOS FM 수신기 프론트엔드 구현

본 논문에서 2개의 다른 특성을 갖는 FM 안테나들을 사용할 수 있도록 자동 변환 매칭 네트워크를 갖는 CMOS FM 수신기 프론트엔드 구조를 제안하였고 이를 65nm CMOS 공정을 이용하여 설계하였다. 제안된 FM 수신기는 높은 주파수 선택 특성을 갖는 임베디드 안테나를 사용 시 FM 전체 주파수 밴드에서 일정한 수신감도를 유지하기 위해서 저 잡음 증폭기의 입력 매칭 회로의 공진 주파수를 채널 주파수에 따라 가변이 가능하도록 구현하였다. 구현된 FM 프론트엔드의 시뮬레이션 결과는 약 38dB 전압이득, 2.5dB 이하의 잡음 지수 특성, -15.5dBm의 IIP3 선형성 특성을 보이고 1.8V 전원에 3.5mA 전류를 소모한다. In this paper, we propose a CMOS FM RX front-end structure with an automatic tunable input matching network and implement it using a 65nm CMOS technology. The proposed FM RX front-end is designed to change the resonance frequency of the input matching network at the low noise amplifier (LNA) according to the channel frequency selected by a phase-locked loop (PLL) for maintaining almost constant sensitivity level when an embedded antenna type with high frequency selectivity characteristic is used for FM receiver. The simulation results of implemented FM front-end show about 38dB of voltage gain, below 2.5dB of noise figure, and -15.5dBm of input referred intercept point (IIP3) respectively, while drawing only 3.5mA from 1.8V supply voltage including an LO buffer.

BST Capacitor Based Tunable Matching Network for SAW Sensors

Surface acoustic wave (SAW) sensors are becoming extremely important in environmental health monitoring by wireless technologies. SAW devices need impedance matching networks at the input and output for efficient power transfer. In this paper, we are presenting the results of tunable matching networks for SAW devices with BST capacitors. We used simple L-matching network implemented with chip inductors and tunable BST capacitors. The characteristics of tunable matching network interfaced to SAW device is simulated using Agilent's ADS simulation tool. The return loss from the SAW devices can be increased and tuned significantly by applying a tuning voltage to the BST capacitors. The SAW device which has been studied is SAW filter.

Microstructure and microwave properties of inkjet printed barium strontium titanate thick-films for tunable microwave devices

Abstract Barium strontium titanate (BST) is a promising material for passive tunable microwave devices such as phase shifters, tunable filters or tunable matching networks. This publication covers the preparation of BST thick-films for microwave applications through inkjet printing. A Ba 0.6 Sr 0.4 TiO 3 ink was prepared, printed on alumina substrates and sintered at temperatures between 1100 °C and 1200 °C. The microstructure of the thick-films reveals the evolution of grain growth and porosity with increasing sintering temperature. Furthermore, a reaction with the substrate was observed for T ≥ 1175 °C. A maximum tunability of 36% was observed at temperatures right below the onset of the substrate reactions. This process conditions were used for the preparation of a loaded line phase shifter, which successfully shows the capability of the inkjet printing process for future microwave device fabrication.

Wide-frequency range, dynamic matching network and power system for the "Shoelace" radio frequency antenna on the Alcator C-Mod tokamak.

A wide-frequency range (50-300 kHz) power system has been implemented for use with a new RF antenna - the "Shoelace" antenna - built to drive coherent plasma fluctuations in the edge of the Alcator C-Mod tokamak. A custom, dynamically tunable matching network allows two commercial 1 kW, 50-Ω RF amplifiers to drive the low-impedance, inductive load presented by the antenna. This is accomplished by a discretely variable L-match network, with 81 independently selected steps available for each of the series and parallel legs of the matching configuration. A compact programmable logic device provides a control system that measures the frequency with better than 1 kHz accuracy and transitions to the correct tuning state in less than 1 ms. At least 85% of source power is dissipated in the antenna across the operational frequency range, with a minimum frequency slew rate of 1 MHz/s; the best performance is achieved in the narrower band from 80 to 150 kHz which is of interest in typical experiments. The RF frequency can be run with open-loop control, following a pre-programmed analog waveform, or phase-locked to track a plasma fluctuation diagnostic signal in real time with programmable phase delay; the amplitude control is always open-loop. The control waveforms and phase delay are programmed remotely. These tools have enabled first-of-a-kind measurements of the tokamak edge plasma system response in the frequency range and at the wave number at which coherent fluctuations regulate heat and particle transport through the plasma boundary.

RF-MEMS variable matching networks and switches for multi-band and multi-mode GaN power amplifiers

This work presents radio-frequency-microelectromechanical-system (RF-MEMS)-based tunable matching networks for a multi-band gallium nitride (GaN) power amplifer (PA) application. In the frequency range from 3.5–8.5 GHz return losses of 5–10 dB were measured for the input network, matching impedances close to the border of the Smith chart. For the output matching network return losses of 10–20 dB and insertion losses of 1.3–2 dB were measured. The matching networks can tune the PA to four different operating frequencies, as well as changing the transistor's mode of operation from maximum delivered-output-power to maximum power-added-efficiency (PAE), while keeping the operating frequency constant. Furthermore, different single pole double throw (SPDT)-switches are designed and characterized, to be used in frequency-agile transmit/receive-modules (T/R modules).

Design and Applications of a 300–800 MHz Tunable Matching Network

In this paper, the optimized design, characterization and applications of a broadband 300-800 MHz (~ 91% fractional bandwidth) digitally-controlled tunable matching network is presented. The design employs PIN diodes as switching components and a repetitive structure of basic cells using lumped reactive elements. After an intensive and complex optimization process, a Smith chart coverage (return losses better than 10 dB and losses lower than 2 dB) above 60% is obtained in all the bandwidth reaching 75% in the middle of the band (400-700 MHz). The potential of the manufactured tunable matching network for antenna mismatch compensation, antenna bandwidth extension and power amplifier efficiency improvement in back-off is showed.

Tunable ferroelectric impedance matching networks and their impact on digital modulation system performance

In this paper the bit error rate performance and error vector magnitude of a tunable impedance matching network is analyzed assuming QPSK, 16-QAM and 64-QAM digital modulation schemes. The characterized tunable impedance matching network is based on barium–strontium–titanate ferroelectric thick-film varactors. Inherent dispersive behavior is subsumed into the forward transmission of the passive device. Due to this nonlinear phase response, in general to maximize the overall system performance, an agile tuning of the varactor values is demonstrated, taking into account the phase and group delay of s21 parameter. Detailed signal simulation results based on measured data of a testbed are presented. The influence of varying matched impedances on the tuning behavior with different modulation bandwidths is discussed at a center frequency of 1.9GHz.

Tunable Matching Network Using MEMS Switches

This paper presents a novel approach in order to construct low-loss reconfigurable impedance matching networks and tuners using MEMS series-contact switches and periodic defected-ground-structures (DGSs) implemented on coplanar waveguide (CPW) transmission lines. The application of DGSs results in an improved insertion loss and power handling capability compared to the conventional RF MEMS impedance tuning networks. The proposed structure consists of 12 DGSs and RF MEMS series-contact switches. The tunable matching network was fabricated on a silicon substrate and is only 1.4×̃˾̈˰̽̽˰̹̾˰̵̹̓͊˾˰̸̵̤˰̵̵̴̱̽̓͂ͅ˰̼̿̓̓˰̶̿˰̸̵̈́˰̵͇̻̾̈́̿͂˰̸̵͇̾˰̵̴̓ͅ˰̈́̿˰̸̱̳̽̈́˰̱˰́̀˰Ω˰̴̼̱̿˰̈́̿˰̅̀˰Ω˰̶͂̿m 5GHz up to 40 GHz is only 0.8 dB. The results show that the tuner can achieve a broadband impedance match for a wide variety of loads that are either purely resistive or that have a large reactance as well.

Preparation of Integrated Passive Microwave Devices Through Inkjet Printing

Barium strontium titanate (BST) is a promising material for passive tunable microwave devices such as phase shifters or tunable matching networks. This publication covers the preparation of BST thick-films for microwave applications through inkjet printing. Two barium strontium titanate (BST) inks were prepared, printed on alumina substrates and sintered at different temperatures. The first ink was prepared with pure BST and sintered between 1100°C and 1200°C. The second ink was prepared with a BST–ZnO–B2O3 composition and was suitable to reduce the sintering temperature down to 800°C. The microstructure of the thick-films reveals the evolution of grain growth with increasing sintering temperature in the thick-films. Furthermore, a reaction with the substrate was observed for both inks at high sintering temperatures. The microwave characterization of the thick-films shows that for the permittivity and the tunability of the films, the effect of grain growth and reaction with the substrate compete against each other. Hence, the optimal microwave properties were achieved at a transition temperature, where first additional phases could already be observed. Even though, the properties are poorer for lower sintering temperatures, the investigations show that the preparation of silver- or gold-based metal–insulator–metal (MIM) structures through inkjet printing is possible with this composition. This allows various new design concepts for partly or fully inkjet printed passive microwave devices. Furthermore, it gives the opportunity for a future integration of passive tunable microwave devices in a low temperature co-fired ceramic (LTCC) fabrication process.