Monolithic Dual-Gate GaAs FET Digital Phase Shifter

The design, fabrication, and characterization of a fully monolithic FET digital phase-shifter circuit is described. The circuit is designed around a unique dual-gate FET structure operating as a switchable single-pole, double-throw amplifier. Each 2.5 X 3.0-mm chip has one bit (e.g., 22.5°, 90°, etc.) of phase control. The circuit, which includes all dc bypass circuitry on-chip, features thin-film lumped element capacitors and inductors, air-bridge crossovers and interconnects, via-hole frontside grounding, and integral beam leads. The fabrication of these elements is described in some detail. The phase-shifter circuit gives a peak gain of 3 dB across a 10-percent bandwidth in X-band. A method of achieving continuous phase and amplitude control using a 90° bit chip is described. Finally, phase performance of a four-bit digital phase shifter realized by cascading four monolithic active phase-shifter chips is reported.     

C波段单片矢量调制器

报道了Ｃ波段单片矢量调制器的设计和制作。采用双栅场效应晶体管（ＤＧＦＥＴ）放大器作为控制器。偏置电路在芯片内。采用集总薄膜电容、电感、电阻作为匹配元件。采用离子注入、背面通孔接地、空气桥跨接等先进工艺技术。描述了ＤＧＦＥＴ器件Ｓ参数的提取步骤。两路放大器和９０°相移网络制作在３．１５ｍｍ×２．５ｍｍ×０．１ｍｍ的芯片上，同相功分器制作在１．６（１．８）ｍｍ×２．９ｍｍ×０．１ｍｍ的芯片上。电路可获得在０～８７°内连续变化的相移量，输出幅度可控。     

A Monolithic Single-Chip X-Band Four-Bit Phase Shifter

X-band GaAs monolithic passive phase shifter with 22.5°, 45°, 90°, and 180° phase bits are developed using FET switches. By cascading all four bits, a four-bit digital phase shifter with 5.1+-0.6-dB insertion loss is realized on a single 6.4 x 7.9 x 0.1-mm chip.     

Ku波段GaAs微波单片集成电路

本文介绍Ku波段GaAs单片集成电路的设计、研制和测量结果。该单片电路的匹配网络采用对FET进行计算机分析和电路模拟相结合的方法进行设计。研制成功了一个两级单片电路,其尺寸为1.9×3.2×0.1mm,在14.5～15.4GHz的频率范围内,输出功率P_0≥100mW,增益G_P≥5dB,带内增益起伏△G_P≤±0.75dB。     

A Ku‐Band 5‐Bit Phase Shifter Using Compensation Resistors for Reducing the Insertion Loss Variation

This paper describes the performance of a Ku‐band 5‐bit monolithic phase shifter with metal semiconductor field effect transistor (MESFET) switches and the implementation of a ceramic packaged phase shifter for phase array antennas. Using compensation resistors reduced the insertion loss variation of the phase shifter. Measurement of the 5‐bit phase shifter with a monolithic microwave integrated circuit demonstrated a phase error of less than 7.5° root‐mean‐square (RMS) and an insertion loss variation of less than 0.9 dB RMS for 13 to 15 GHz. For all 32 states of the developed 5‐bit phase shifter, the insertion losses were 8.2 ± 1.4 dB, the input return losses were higher than 7.7 dB, and the output return losses were higher than 6.8 dB for 13 to 15 GHz. The chip size of the 5‐bit monolithic phase shifter with a digital circuit for controlling all five bits was 2.35 mm × 1.65 mm. The packaged phase shifter demonstrated a phase error of less than 11.3° RMS, measured insertion losses of 12.2 ± 2.2 dB, and an insertion loss variation of 1.0 dB RMS for 13 to 15 GHz. For all 32 states, the input return losses were higher than 5.0 dB and the output return losses were higher than 6.2 dB for 13 to 15 GHz. The size of the packaged phase shifter was 7.20 mm × 6.20 mm.     

A production ready, 6-18-GHz, 5-b phase shifter with integratedCMOS compatible digital interface circuitry

A producible, high-yield, monolithic 6-18-GHz, 5-b phase shifter with integrated standard CMOS compatible digital interface circuitry has been developed for use over the -55 to +90°C temperature range. Differential phase shift is achieved using high-pass and low-pass filter structures. The integrated digital interface circuitry produces complementary outputs that are used to bias the phase-shifter bits. The integration of the digital interface circuitry, made with microwave FETs, reduced the phase-shifter bit control bias lines by a factor of 2. The phase shifter was fabricated at both Raytheon's and Texas Instruments' GaAs foundries in production quantities using a standard microwave process. Complete on-wafer RF tests were performed to screen the phase-shifter circuits and determine electrical yield. The phase shifter has an r.m.s. phase error <10° from 6.5 to 18 GHz, maximum insertion loss of 14 dB, and an r.m.s. amplitude error <0.8 dB over the 6-18-GHz band     

A Ka-Band GaAs Monolithic Phase Shifter

The design and performance of a GaAs monolithic 1800 one-bit switched line phase shifter test circuit for Ka-band operation is presented. A self-aligned gate (SAG) fabrication technique is also described that reduces resistive parasitic in the switching FET's. Over the 27.5-30 GHz band, typical measured differential insertion phase is within 10-20° of the ideal time delay characteristic. Over the same band, the insertion loss for the SAG phase shifter is about 2.5-3 dB per bit. The SAG fabrication technique holds promise in reducing phase shifter insertion loss to about 1.5 dB/bit for 30-GHz operation.     

X波段4bit MMIC数字移相器的设计与实现

基于WIN 0.25 μm GaAs赝配高电子迁移率晶体管(PHEMT)工艺,设计并制备了一款X波段4 bit单片微波集成电路(MMIC)数字移相器.22.5°和45°移相单元采用开关滤波型拓扑结构,90°和180°移相单元采用高低通滤波型拓扑结构.对拓扑结构工作原理进行分析,并采用ADS2014软件完成电路的电磁仿真及优化.测试结果表明,该4 bit MMIC数字移相器获得了优良的宽带性能,且与仿真结果吻合良好.在8～ 13 GHz频带内,移相器的均方根(RMS)相位精度误差小于6.5°,插入损耗优于-6.8 dB,RMS插入损耗波动低于0.5 dB,输入回波损耗优于-13 dB,输出回波损耗优于-9.5 dB.该4 bit MMIC数字移相器在相对带宽为47％的X频段内性能优良,适用于有源相控阵雷达等通信系统中.     

A Low-Loss Ku-Band Monolithic Analog Phase Shifter

A GaAs monolithic Ku-band analog phase shifter integrating 90° branch line coupler with planar varactor diodes has been fabricated for the first time. A phase shift of 109° +- 3° with an insertion loss of 1.8+-0.3 dB was measured from 16 to 18 GHz. A 360° phase shifter with 4.2+-0.9 dB insertion loss was realized in the same frequency range by connecting three phase-shifter chips in series. To our knowledge, this is the lowest insertion loss obtained by a 360° Ku-band phase shifter using monolithic circuits. In addition, hyperabrupt varactors using nonuniform doping profiles increased the phase shift by more than 30° and produced a more linear dependence of phase shift on control voltage.     

Monolithic GaAs interdigitated couplers

This paper described the design, fabrication, and performance of two monolithic GaAs C-band 90° interdigitated couplers with 50- and 25-ω impedances, respectively. A comparison of the performance of these two couplers show that the 25-ω coupler has the advantages of lower loss and higer fabrication yield. the balanced amplifier configuration using 25-ω couplers will require a fewer member of elements in the input-output matching circuit of the FET amplifier. The fewer number of matching elements results in great savings in the GaAs real estate for microwave monolithic integrated circuits (MIMIC's). Both the couplers have been fabricated on a 0.1-mm-thick GaAs SI substrate. The measured results agree quite well with calculated results. The losses of the 50- and 25-ω couplers are 0.5 and 0.3 dB, respectively, over the 4-8-GHz frequency band.     

GaAs monolithic Lange and Wilkinson couplers

An important part of monolithic microwave integrated circuits are the passive distributed circuit elements which divide and combine RF signals. This paper describes the design and performance of a monolithic GaAs X-band three-port Wilkinson coupler [1] and a monolithic GaAs X-band four-port interdigitated Lange coupler [2], [3]. These couplers are useful both as power dividers and power combiners. In the Wilkinson, the input power is split equally between the output ports with zero differential phase shift. For the Lange, there is a phase difference of 90° between the outputs. All ports are well matched and the output ports are highly isolated. The transmission mode chosen for these couplers is microstrip on semi-insulating GaAs with conductor-to-ground plane spacing of 0.1 mm. This low-loss, high permittivity medium is compatible with the present monolithic GaAs FET technology which thus allows combining more complicated monolithic microwave integrated circuits on a single chip. The fabrication process takes advantage of the technology developed for proeessfng GaAs FET's. For example, connecting the coupling conductors for the Lange coupler requires RF crossovers. To minimize crossover capacitance, an air-bridge interconnection technique is used. Calculated coupling, isolation, and VSWR data for the Wilkinson and Lange couplers are compared with actual measured performance showing good agreement with expected results. Measured loss, minus fixture contributions, shows 0.25 dB for the Wilkinson and 0.75 dB for the Lange.     

A novel MMIC X-band phase shifter

A novel configuration for monolithic phase shifters is presented. The layout and fabrication of a single chip, four-bitX-band phase shifter, measuring 3.7 × 2.3 mm, is described in some detail. The first samples to be assessed exhibited full 360 ° coverage at the design frequency, operation throughout X-band, good matches, and an insertion loss less than 5 dB.     

Monolithic GaAs Interdigitated Couplers

This paper deseribes the design, fabrication, and performance of two monolithic GaAs C-band 90° interdlgitiited couplers with 50- and 25-Omega impedances, respectively. A comparison of the performance of' these two couplers shows that the 25-Omega coupler has the advantages of lower loss and bigher fabrication yield. The bafanced amplifier configuration rising 25-Omega couplers will require, a fewer number of elements in the input-output matching circuit of the FET amplifier. The fewer number of matcfdng elements results in great savings in the GaAs real estate for microwave monolithic intergrated circuits (MMIC's). Both the couplers have been fabricated on a 0.1-mm-thick GaAs S1 substrate. The measured results agree quite well with calculated results. The losses of the 50- and 25-Omega couplers are 0.5 and 0.3 dB, respectively, over the 4-8-GHz frequency band.     

Design and performance of a Ka-band monolithic phase shifterutilizing nonresonant FET switches

This paper describes design consideration and performance of a Ka-band monolithic phase shifter utilizing nonresonant FET switches. The switches show broad-band on/off characteristics up to 60 GHz without using inductors; thus, robust circuit design is possible for a switched-line phase shifter. To determine circuit topology, we introduce a schematic design approach. As a result, desired phase shift as well as good matching characteristics can be realized. The developed 4-bit monolithic phase shifter demonstrates an overall phase deviation less than 5° rms and an insertion loss variation less than 0.65 dB rms from 33 to 35 GHz. For all 16 states, the insertion loss is measured to be 13.1±1.1 dB and the VSWR is less than 1.6. The chip size of the monolithic phase shifter is 2.5 mm×2.2 mm     

Phase Shifts in Single- and Dual-Gate GaAs MESFET's for 2-4-GHz Quadrature Phase Shifters

The variation of transmission phase for single- and dual-gate GaAs MESFET's with bias change and its probable effects on the performance of an active phase shifter have been studied for the frequency range 2 to 4 GHz. from measured S-parameter values for single- and dual-gate transistors, the element values of the equivalent circuits were fitted by using the computer-aided design program SUPER COMPACT. For the normal full-gate voltage range 0 to -2 V at V/sub DS/= 4 V, the single-gate MESFET varies in transmission phase from 142° to 149° at 2 GHz, and from 109° to 119° at 4 GHz. However, with drain voltage varied from 0.3 to 4 V and a constant gate-voltage bias of 0 V, the phase shifts are much larger, 105° to 145° at 2 GHz and 78° to 112° at 4 GHz. this suggests that large phase shifts may be expected in a dual-gate device and this is found to be so. With V/sub DS/= 4 Vand V/sub GS1/= - 1.0 V, variation of control (second) gate bias from 0 to - 1.75 V for the NE463 GaAs MESFET produces a transmission phase variation from 95° to 132° at 2 GHz and 41° to 88° at 4 GHz. Such phase shifts cause both amplitude and phase errors in phase-shifter circuits of the kind where signals from two FET channels are combined in quadrature with their gate voltages controlled to provide 0° to 90° phase control with constant amplitude. For the single-gate FET examined, the expected amplitude and phase errors are 0.30 dB and 6° at 2 GHz, and 0.36 dB and 10° at 4 GHz. If dual-gate FET's are used in similar circuits, the distribution of errors is different. For NE463 devices, the corresponding figures are 0.56 dB and 2° at 2 GHz and 1.2 dB and 3° at 4 GHz. the advantage of the dual-gate configuration is that the input impedance conditions are more constant than for the single-gate configuration.     

A compact, monolithic microwave demodulator-modulator for 64-QAMdigital radio links

The design, fabrication and performance of a monolithic microwave direct modulation modulator-demodulator are presented. The subsystem is designed to work in a 64-QAM digital radio link. At this level of modulation, it is necessary to have some possibilities of phase and amplitude trimming by external voltages to achieve sufficient accuracy. The circuit includes elementary functions such as quadrature and in-phase splitters, and circuits giving the possibility to adjust phases and amplitudes for 64 QAM and higher level modulation. The design is such that the same chip can be used either as a direct demodulator or as a modulator. This complex circuit of small dimensions (2.7 mm×3.65 mm) exhibits good demodulation and modulation performances. The overall performances of this monolithic circuit are achieved without degrading the DC yield     

A 14-bit monotonic NMOS D/A converter

A new configuration of a 14-bit digital-to-analog (D/A) converter has been fabricated as an experimental monolithic NMOS chip. The concept utilizing two cascaded resistor strings delivers an inherent 14 bit monotonicity and a static voltage output signal. The small chip size of about 8.5 mm/SUP 2/ and the saving of external components make the converter applicable for low-cost high-resolution control loop systems. A modified test chip is also described which has been provided as a step into the field of accurate monolithic converters needed for digital audio systems. A voltage output settling time less than 10 /spl mu/s and a linearity at the 12 bit level have been achieved.     

一种场效应管预失真电路对改善行波管非线性的作用

该文利用场效应管的非线性作用,替代通常预失真线性化电路中的衰减器和移相器,使这种预失真器在相位扩张量变化较小的同时,可以对增益扩张量进行调节控制,有效提升了预失真电路改善行波管非线性的作用。实际设计电路实验表明,在频率为8.38-8.58 GHz和额定输入功率范围内,设计了实际电路并完成相应的实验,获得了6 dB和45的增益和相位扩张以及15.4 dB的载波与交叉调制分量比值的改善。     

Design, fabrication, and characterization of monolithic microwave GaAs power FET amplifiers

The design, fabrication, and characterization of three- and four-stage monolithic GaAs power FET amplifiers are described. Each of the amplifier chips measures 1 mm × 4 mm. Procedures for characterizing these monolithic amplifiers are outlined. Output powers of up to 1 W with 27-dB gain were achieved with a four-stage design near 9 GHz. The circuit topologies used were flexible enough to allow external bondwires to be used as shunt inductors for amplifier operation at C- or S-bands. An output power of 2 W with 28-dB gain and 36.6-percent power-added efficiency was achieved at 3.5 GHz, using a modified four-stage amplifier.     

L- and S-Band Compact Octave Bandwidth 4-bit MMIC Phase Shifters

This paper presents the design approach and test results of L- and S-band compact monolithic microwave integrated circuit (MMIC) phase shifters (PSs) developed for octave band applications. The PS designs were based on an optimum topology selected for each bit for compact size and low insertion loss, and have on-chip integrated digital control. The MMIC PSs were fabricated employing GaAs-based high-performance 0.4-mum MSAG MESFET technology with multilevel-plating process. We achieved a chip size of 2.6 mm², the smallest size reported to date.