Silicon IMPATT cascaded amplifier: 6 W (c.w.) at 9.6 GHz

A compact silicon IMPATT 4-stage coaxial amplifier has given 6.3 W (c.w.) with a power gain of 28 dB and an instantaneous bandwidth (?1 dB) of 200 MHz centred at 9.6 GHz. A gain ripple of less than 0.2 dB and phase deviation from linearity of ±3° across a 30 MHz bandwidth slot was obtained at the full rated output power. The overall efficiency was 4.5%. Commercial devices and circulators were used throughout the unit and the power in the final stage was obtained by combining the available powers from four separate devices. Particular attention was paid to the circuits to reduce the onset of spurious oscillations under large-signal conditions.     

A Two-Stage IMPATT-Diode Amplifier

The system aspects and packaging of a two-stage FM IMPATT-diode amplifier are described. The amplifier combines the output power of 4 IMPATT diodes in the final stage to provide an output power of greater than 4 W at 6 GHz. The system has a locking bandwidth of greater than 200 MHz with a 16-dB gain and a noise figure of less than 50 dB. Both the design and the experimental performance of the amplifier and each of its stages are discussed. The noise characterization of IMPATT-diode amplifiers, operating as injection-locked oscillators or stable amplifiers, determined the mode of operation for each stage. Included in the paper are experimental results of large-signal noise characterization of both Si and GaAs IMPATT diodes, as are the noise characteristics related to the output power and gain.     

CW microwave amplification from circuit-stabilized epitaxial GaAs transferred electron devices

Stable c.w. reflection-type amplification at C- X-band frequencies has been obtained from circuit-stabilized GaAs transferred electron devices biased as high as three times threshold. An instantaneous fractional bandwidth exceeding 50% and a small-signal linear gain near 10 dB have been realized with a single device for center frequencies from 5.0 to 9.0 GHz. A -1-dB-gain compression-power output typically above 100 mW and a total saturated power output near 1 W have been measured. A narrow-band doubly tuned amplifier response with a linear gain of 40 dB has also been measured. With a noise figure of 15 dB, these amplifiers have a dynamic range in excess of 90 dB. Highly nonlinear effects have been observed for large-signal narrow-band operation. Both gain and hysteresis effects have been observed. Large-signal effects of bias, frequency, and power level on amplifier performance have been measured.     

Hybrid integrated lumped-element microwave amplifiers

This paper describes the development of microwave lumped-element thin-film amplifiers. The basic design philosophy underlying lumped inductors and capacitors at microwave frequencies is reviewed, showing how Q's of 100 are achieved. A variety of tunable input, output, and interstage integrated lumped-element networks for transistor amplifiers were fabricated. The gain and efficiency of 2-GHz class-C operated transistors mounted in these circuits were comparable with the best performance achieved by the same transistors in less lossy coaxial circuits. The measured losses (1.2 dB) at 2 GHz were very close to those calculated using the design parameters. Single-stage amplifiers at 2 GHz achieved one watt of output power with 4 dB of gain. At somewhat lower power levels more than 6 dB of gain was achieved. The circuits allowed the operation of low-power level class-A amplifiers with over 13 dB of gain. Cascaded operation yielded more than 17 dB of gain with 0.8 watts of CW power. It is concluded that lumped elements can be fabricated by thin-film technology and will play an important role in microwave integrated circuits.     

Hybrid Integrated Lumped-Element Microwave Amplifiers

This paper describes the development of microwave lumped-element thin-film amplifiers.The basic design philosophy underlying lumped inductors and capacitors at microwave frequencies is reviewed, showing how Q's of 100 are achieved. A variety of tunable input, output, and interstage integrated lumped-element networks for transistor amplifiers were fabricated.The gain and efficiency of 2-GHz class-C operated transistors mounted in these circuits were comparable with the best performance achieved by the same transistors in less lossy coaxial circuits. The measured losses (1.2 dB) at 2 GHz were very close to those calculated using the design parameters. Single-stage amplifiers at 2 GHz achieved one watt of output power with 4 dB of gain. At somewhat lower power levels more than 6 dB of gain was achieved. The circuits allowed the operation of low-power level class-A amplifiers with over 13 dB of gain. Cascaded operation yielded more than 17 dB of gain with 0.8 watts of CW power. It is concluded that lumped elements can be fabricated by thin-fihn technology and will play an important role in microwave integrated circuits.     

Hybrid Integrated Lumped-Element Microwave Amplifiers

This paper describes the development of microwave lumped-element thin-film amplifiers. The basic design philosophy underlying lumped inductors and capacitors at microwave f requencies is reviewed, showing how Q's of 100 are achieved. A variety of tunable input, output, and interstage integrated lumped-element networks for transistor amplifiers were fabricated. The gain and efficiency of 2-GHz class-C operated transistors mounted in these circuits were comparable with the beat performance achieved by the same transistors in less Iossy coaxial circuits. The measured losses (1.2 dB) at 2 GHz were very close to those calculated using the design parameters. Single-stage amplifiers at 2 GHz achieved one watt of output power with 4 dB of gain. At somewhat lower power levels more than 6 dB of gain was achieved. The circuits allowed the operation of low-power level class-A amplifiers with over 13 dB of gain. Cascaded operation yielded more than 17 dB of gain with 0.8 watts of CW power. It is concluded that lumped elements can be fabricated by thin-film technology and will play an important role in microwave integrated circuits.     

Design of Broad-Band GaAs FET Power Amplifiers

A direct systematic approach to designing broad-band GaAS FET power amplifiers for optimum large-signal gain performance is described. Assets of this approach include its accuracy in predicting large-signal amplifier performance and its basic simplicity. The implementation of the technique is facilitated by having to measure large-signal device bebavior at only one single frequency. The practicability of the method is demonstrated through comparisons between measured and predicted results.     

Nonlinear and Large-Signal Characteristics of Millimeter-Wave IMPATT Amplifiers

Experimental results obtained with millimeter-wave IMPATT amplifiers are presented. Nonlinear and large-signal characteristics of stable IMPATT amplifiers and injection-locked IMPATT oscillators are described. Amplifier circuit configuration, diode characteristics, and measured effects of bias current, temperature, and large-signal level on gain, bandwidth, power saturation, and phase-delay characteristics are discussed in detail.     

Optimization of Third-Order Intermodulation Product and Output Power from an X-Band MESFET Amplifier Using Volterra Series Analysis

A third-order analysis for accurately predicting large-signal power and intermodulation distortion performance for GaAs MESFET amplifiers is presented. The analysis is carried out for both single- and two-tone input signals using the Volterra series representation and is based only on small-signal measurements. Simple expressions for the nonlinear power gain frequency response, the output power, the gain compression factor, and the third-order intermodulation (IM/sub 3/) power are presented. The major sources of gain compression and intermodulation distortion are identified. Based on the developed nonlinear analysis in conjunction with the device nonlinear model, a systematic procedure for designing a MESFET amplifier under large-signal conditions for optimum output power and IM/sub 3/ performance is proposed. The method utilizes out of band computed matching compensation through a nonlinear model of the amplifier. The accuracy of the device large-signal and IM/sub 3/ distortion characterization and the practicability of the proposed method are illustrated through comparison between measured and predicted results.     

Low-noise wideband indium-phosphide transferred-electron amplifiers

X band pulsed, InP transferred-electron reflection amplifiers have been characterised by a study of the small-signal admittance, the large-signal dynamic conductance and the noise figure. These measurements have been made as functions of voltage, frequency and temperature on a number of different vapour epitaxial layers. The lowest observed noise figure was 8.8 dB at 10.0 GHz. An instantaneous bandwidth of more than 4 GHz at 7 dB gain has been obtained using a simple impedance-equalisation circuit.     

全光纤结构高增益脉冲光纤放大器的实验研究

为了探讨多级级联掺镱光纤放大器的脉冲放大特性,采用主振功率放大技术(MOPA),实验研究了3级级联、全光纤结构的高增益脉冲激光放大器。通过优化各放大级增益光纤的长度和抽运光功率的大小,在保证高放大增益的同时,抑制了掺镱光纤中自发辐射光的自生激光振荡,并对第2放大级进行了结构优化。在脉冲激光放大过程中实现了中心波长1064nm、脉冲宽度19ns、重复频率5kHz、峰值功率3.8kW、总放大增益达43.8dB的稳定激光输出。同时,制作完成了1台结构紧凑、全光纤结构的脉冲光纤放大器样机,对重复频率1Hz的低频脉冲信号进行了放大实验,也得到了43.2dB的输出信号增益。结果表明,本脉冲光纤放大器对低频脉冲信号有很好的放大效果。     

Power performance and scalability of AlGaN/GaN power MODFETs

The scalability of power performance of AlGaN/GaN MODFETs with large gate periphery, as necessary for microwave power devices, is addressed in this paper. High-frequency large-signal characteristics of AlGaN/GaN MODFETs measured at 8 GHz are reported for devices with gatewidths from 200 μm to 1 mm. 1-dB gain compression occurred at input power levels varying from -1 to +10 dBm as the gatewidth increased, while gain remained almost constant at -17 dB. Output power density was ~1 W/mm for all devices and maximum output power (29.9 dBm) occurred in devices with 1-mm gates, while power-added efficiency remained almost constant at ~30%. The large-signal characteristics were compared with those obtained by dc and small-signal S-parameters measurements. The results illustrate a notable scalability of AlGaN/GaN MODFET power characteristics and demonstrate their excellent potential for power applications     

Large-signal noise, frequency conversion, and parametric instabilities in IMPATT diode networks

A theoretical treatment is presented of some of the nonlinear properties of the IMPATT or Read avalanche diode, a negative-resistance semiconductor device that is now coming into wide-spread use for microwave oscillators and power amplifiers. Based upon the somewhat idealized Read model, this theory presents a qualitatively meaningful explanation of certain "parametric" effects that are often troublesome to the designers of amplifier and oscillator networks. First, an analytic treatment is given for frequency-conversion effects that appear when the device is strongly driven by one continuous signal, and simultaneously perturbed by a weak signal at another frequency or by noise. From this theory, stability criteria are derived for spurious oscillations of the "parametric" type which frequently appear in these devices under large-signal conditions. The noise-generation mechanism is reviewed, and it is shown that the noise is enhanced by strong signals and the spectral distribution is modified by frequency conversion. Some measurements of noise and frequency-conversion gain are presented which indicate substantial qualitative agreement with the theory.     

Thick-film 3-stage m.i.c. IMPATT diode-amplifier on ferrite

A 3-stage hybrid m.i.c. gallium-arsenide IMPATT-diode amplifier is described with an output of 1.05 W at 9.2 GHz, a large-signal gain of 21 dB and a bandwidth to ?3 dB greater than 1 GHz; the amplifier is stable at all input levels. The concept of an effective radius, first proposed to explain the properties of disc capacitors, has been used successfully in the circulator design. Close attention has been paid to screening the unencapsulated diodes to prevent r.f. radiation and to incorporating resistive-loading circuits to suppress spurious out-of-band oscillations.     

A frequency-controlled active phased array

A frequency-controlled active phased array is introduced for cost-effective base-station applications. The array realizes simple LO-controlled beam steering with a fixed RF frequency, but without phase shifter components. Primary beam squint and pattern distortions, often seen in typical frequency-controlled phased arrays, are substantially reduced by the use of our heterodyne-mixing scheme and new feed network structures. The MMIC amplifiers provide more than 20 dB gain for a desired RF signal at 20 GHz, and effectively suppress the unwanted sideband and spurious LO by more than 40 dB. The K-band transmitter array demonstrates up to 40 degree beam-steering within 0.5 degree scan error and less than 1.3 dB gain error during scanning.     

RF Amplifier Design with Large-Signal S-Parameters

High-power UHF transistors have been characterized through the use of large-signal S-parameters. These S-parameters have been used successfully to design UHF power amplifiers. Waveform measurements show that due to the Q of the package parasitic, most class C operated UHF power transistors have nearly sinusoidal waveforms at their package terminals. Experimental evidence presented shows that the large-signal S-parameters are relatively independent of power once the device is turned on. These two observations make it possible to extend modified small-signal S-parameter design techniques to large-signal power amplifiers.     

Dual-gate AlGaN/GaN modulation-doped field-effect transistors with cut-off frequencies f/sub T/>60 GHz

We demonstrate dual-gate AlGaN/GaN modulation-doped field-effect transistors (MODFETs) with gate-lengths of 0.16 /spl mu/m and 0.35 /spl mu/m for the first and second gates, respectively. The dual-gate device exhibits a current-gain cut-off frequency f/sub T/>60 GHz, and can simultaneously achieve a high breakdown voltage of >+100 V. In comparison to single-gate devices with the same gate length 0.16 /spl mu/m, dual-gate FETs can significantly increase breakdown voltages, largely increasing the maximum allowable drain bias for high power application. The continuous wave (CW) output power is in excess of 3.5 W/mm at 8.2 GHz. The corresponding large-signal gain is 12 dB and the power added efficiency is 45%. The dual-gate device with different gate lengths shows the capability of providing simultaneous high cut-off frequencies, and high breakdown voltages for broadband power amplifiers.     

毫米波大动态宽带单片低噪声放大器

利用0.25μmGaAsPHEMT低噪声工艺,设计并制造了2种毫米波大动态宽带单片低噪声放大器。第1种为低增益大动态低噪声放大器,单电源+5V工作,测得在26～40GHz范围内,增益G=10±0.5dB,噪声系数NF≤2.2dB,1分贝压缩点输出功率P1dB≥15dBm;第2种为低压大动态低噪声放大器,工作电压为3.6V,静态电流0.6A(输出功率饱和时,动态直流电流约为0.9A),在28～35GHz范围内,测得增益G=14～17dB,噪声系数约4.0dB,1分贝压缩点输出功率P1dB≥24.5dBm,最大饱和输出功率≥26.8dBm,附加效率约10%～13.6%。结果中还给出了2种放大器直接级联的情况。     

165-GHz Transceiver in SiGe Technology

Two D-band transceivers, with and without amplifiers and static frequency divider, transmitting simultaneously in the 80-GHz and 160-GHz bands, are fabricated in SiGe HBT technology. The transceivers feature an 80-GHz quadrature Colpitts oscillator with differential outputs at 160 GHz, a double-balanced Gilbert-cell mixer, 170-GHz amplifiers and broadband 70-GHz to 180-GHz vertically stacked transformers for single-ended to differential conversion. For the transceiver with amplifiers and static frequency divider, which marks the highest level of integration above 100 GHz in silicon, the peak differential down-conversion gain is -3 dB for RF inputs at 165 GHz. The single-ended, 165-GHz transmitter output generates -3.5 dBm, while the 82.5-GHz differential output power is +2.5 dBm. This transceiver occupies 840 mum times 1365 mum, is biased from 3.3 V, and consumes 0.9 W. Two stand-alone 5-stage amplifiers, centered at 140 GHz and 170 GHz, were also fabricated showing 17 dB and 15 dB gain at 140 GHz and 170 GHz, respectively. The saturated output power of the amplifiers is +1 dBm at 130 GHz and 0 dBm at 165 GHz. All circuits were characterized over temperature up to 125degC. These results demonstrate for the first time the feasibility of SiGe BiCMOS technology for circuits in the 100-180-GHz range.     

Computer simulation of InP transferred-electron amplifiers for Ka-band

A displaced Maxwellian approach which includes relaxation effects is used to simulate small- and large-signal InP transferred-electron amplifiers operating inKa-band. The devices considered are short-circuit stable; that is, they have a subcritical doping-length product. The performance of amplifiers having the usual n⁺-cathode contacts, and p-type notch-cathode contacts designed to produce a uniform electric field, are compared. It is found that the notch contacts have a moderate influence on small-signal characteristics, and a profound influence on large-signal performance. Small-signal bandwidths of 65 percent are predicted for both types of contacts. The saturation efficiency of amplifiers, biased at three times threshold, is much higher for the notch-contact device with values near 5 percent being predicted. The nonlinearity of the large-signal gain characteristic is shown to vary greatly as the frequency deviates from the optimum value.