A 44 GHz HEMT amplifier

A 44-GHz amplifier using 0.25-μm gate length and double-heterojunction structure HEMT devices is described. Higher gain and power performance have been obtained from the amplifier using this device at millimeter-wave frequencies. A spot gain of 9.4 dB and a 1-dB gain compression point of +7.5 dBm has been achieved at 43.5 GHz.     

The DEMATRON—A new crossed-field amplifier

A nonreentrant beam, distributed-emission, crossed-field, forward-wave amplifier, the DEMATRON, is described. The difficulties encountered by early experimenters in achieving gain in excess of 6 db in nonreentrant, crossed-field amplifiers are overcome in the DEMATRON by use of either an electron velocity taper or circuit velocity taper. A crossed-field amplifier design theory is given which is based on the use of equivalent magnetrons, and which takes into account the need for velocity compensation. In practice, electron velocity compensation is accomplished by either changing the sole-anode spacing, or by varying the dc magnetic field or a combination of both. Experiments with the DEMATRON have yielded gains in excess of 10 db over a 15 per cent bandwidth. Power levels between 300 and 500 kw have been achieved at an operating voltage of 25 kv. The design theory has been experimentally shown to be quite satisfactory in the large-signal, saturated gain region of operation, However, the lack of adequate small-signal theory has thus far prevented full optimization of the velocity compensation.     

The magnetron as a negative-resistance amplifier

A one-port, nonlinear, crossed-field microwave amplifier which uses a magnetron as a negative-resistance element is described. Such an amplifier is characterized as one using an emitting sole, reentrant beam, and reentrant RF fields. A circulator is required to achieve stable regenerative amplification. The system is analyzed as a negative-resistance amplifier and as a synchronized or forced oscillator. Experimental measurements of gain and bandwidth are illustrated. The effect of varying operating conditions upon these characteristics is indicated. Operation with a solid cathode composed of oxidized beryllium-nickel has been demonstrated.     

1.7 Volt, DC to 15 GHz Differential Amplifier with Constant Group Delay in InP-HBT Technology

10 dB gain–, 15 GHz-Bandwidth amplifier has been designed andfabricated in InP-HBT technology. Operation of the amplifier was achieved at1.7 V at total current consumption of 40 mA. The amplifier designed to havea Bessel-transfer-function has almost constant group delay up to 30 GHz.Pulse- and eye-diagram- measurements have been performed to verify largesignal operation. At 3.3 V, 24 dB gain and 10 GHz bandwidth was achieved.The 1dB compression point at 1.7 V supply voltage is measured at –10dBm output power.     

38 GHz, coplanar waveguide GaAs MMIC amplifier

A GaAs MMIC coplanar waveguide amplifier is presented. It is realised on a 100 μm-thick substrate, thus leading to compatibility with microstrip circuits. An amplifier stabilisation technique is presented. It is shown that very good agreement between predictions and measurements may be obtained without any time-expensive bi- (tri-) dimensional electromagnetic simulation. The amplifier gain is ~15 dB at 38 GHz, and return losses are better than -18 dB     

A high-yield, 3—7-GHz, 0.5-W push-pull GaAs MMIC amplifier

A high-yield, 3-7-GHz, 0.5-W MMIC GaAs amplifier has been successfully designed and tested. The amplifier features small chip size (1.2 mm sq.), high gain (12 ± 1.5 dB), high power-added efficiency (20 percent), good RF yield (57 percent, and high tolerance to process variations. Packaged amplifiers were built with this chip for both the 2-6-GHz and the 5.9-6.4-GHz bands. Saturated output power of 25 dBm was achieved in the 2-6-GHZ band, and 27 dBm in the 5.9-6.4-GHz band. Infrared measurements show that the device has low FET channel temperatures when operated at full bias power over the full range of military ambient temperatures.     

110-120-GHz monolithic low-noise amplifiers

The authors discuss the development of 110-120-GHz monolithic low-noise amplifiers (LNAs) using 0.1-mm pseudomorphic AlGaAs/InGaAs/GaAs low-noise HEMT technology. Two 2-stage LNAs have been designed, fabricated, and tested. The first amplifier demonstrates a gain of 12 dB at 112 to 115 GHz with a noise figure of 6.3 dB when biased for high gain, and a noise figure of 5.5 dB is achieved with an associated gain of 10 dB at 113 GHz when biased for low-noise figure. The other amplifier has a measured small-signal gain of 19.6 dB at 110 GHz with a noise figure of 3.9 dB. A noise figure of 3.4 dB with 15.6-dB associated gain was obtained at 113 GHz. The authors state that the small-signal gain and noise figure performance for the second LNA are the best results ever achieved for a two-stage HEMT amplifier at this frequency band     

A high-harmonic gyro-klystron amplifier: theory and experiment†

Experimental results of a high-harmonic gyro-klystron amplifier are presented along with small-signal theory and large-signal simulation data. In this device, axis-encircling electrons interact synchronously with high-order azimuthal cylindrical-cavity TE modes. Gain in excess of 20 dB has been achieved at the fifth and sixth harmonics of the cyclotron frequency. The requisite high-energy beam is provided by a gyro-resonant RF accelerator. Harmonic operation together with RF acceleration potentially constitute a compact high-power high-frequency amplifier.     

Gain dynamics of semiconductor optical amplifiers and three-wavelength devices

A numerical model that accounts for the effects of the amplified spontaneous emission (ASE) on the carrier dynamics in a travelling wave semiconductor optical amplifier is presented. The ASE is modeled using effective parameters that are derived starting from the spontaneous emission and gain models. The gain dynamics are then analyzed using the parameters extracted from measurements on a real device to explain the overshoot in the gain recovery. The model is also used to simulate the gain recovery in a three-wavelength device configuration for various injected powers and wavelengths. The recovery time when the injected beam is at the device transparency wavelength is also analyzed with particular attention to the differences between co- and counter-propagating configurations.     

自调制重入式正交场放大器的模拟设计

介绍一种自调制重入式冷阴极正交场放大器 (CFA)。它仅用高频输入信号进行脉冲自调制。实验与研究均表明 :在X波段 ,CFA增益超过 12dB ,带宽 6 %～ 8%的电子效率大于 4 0 % ,阳极电压 8 2kV时 ,输出功率 4 5kW。     

GaAs Dual-Gate FET for Operation Up to K-Band

A high-frequency equivalent circuit model of a GaAs dual-gate FET and analytical expressions for the input/output impedances, transconductance, unilateral gain, and stability factor are presented in this paper. It is found that the gain of a dual-gate FET is higher than that of a single-gate FET at low frequency, but it decreases faster as frequency increases because of the capacitive shunting effect of the second gate. A dual-gate power FET suitable for variable gain amplifier applications up to K-band has been developed. At 10 GHz, a I.2-mm gatewidth device has achieved an output power of 1.1 W with 10.5-dB gain and 31-percent power-added efficiency. At 20 GHz, the same device delivered an output power of 340 mW with 5.3-dB gain. At K-band, a dynamic gain control range of up to 45 dB was obtained with an insertion phase change of no more than +-2 degrees for the first 10 dB of gain control.     

A SiGe MMIC variable gain cascode amplifier

A silicon-germanium variable gain cascode amplifier has been developed to combine the functionality of an amplifier and an attenuator into one monolithic microwave integrated circuit (MMIC). The cascode amplifier, which was designed for a 7-11 GHz frequency range, achieved a gain of 12.5 dB, an input return loss of 7.5 dB, and an output return loss of 12.5 dB. The cascode amplifier exhibited 16 dB of gain control.     

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.     

An optical power equalizer based on one Er-doped fiber amplifier

A device which exhibits zero or slightly negative differential optical gain over a broad input power range is demonstrated. The scheme is based upon saturation enhancement by bidirectional signal input in an Er-doped fiber amplifier. Power equalization of better than 1.2 dB over a 14-dB dynamic input power range is achieved at the 1530-nm signal wavelength. The noise figure penalty due to the equalization is below 3 dB as evaluated by a device simulation     

System performance of optical fibre preamplifier

An optical fibre amplifier has been used as an optical preamplifier for a PIN detector-based receiver. A maximum amplifier gain of 22 dB has been measured and, at this gain with no additional optical filtering, an improvement of 10.5 dB in receiver sensitivity has been achieved.<>     

应用于无线传感器网络低噪声放大器的设计

本文给出一种应用于无线传感器网络射频前端低噪声放大器的设计,采用SMIC0．18μmCMOS工艺模型。在CadenceSpectre仿真环境下的仿真结果表明：该低噪声放大器满足射频前端的系统要求,在2．45GHz的中心频率下增益可调,高增益时,噪声系数为2．9dB,输入P1dB压缩点为-19．8dBm,增益为20．5dB;中增益时,噪声系数为3．6dB,输入P1dB压缩点为-15．8dBm,增益为12．5dB;低增益时,噪声系数为6．0dB,输入P1dB压缩点为-16．4dB,增益为2．2dB。电路的输入输出匹配良好,在电源电压1．8V条件下,工作电流约为6mA。     

Characteristics and Optimum Operating Parameters of a Gyrotron Traveling Wave Amplifier

Characteristics and optimum operating parameters are determined for a new type of high-power high-efficiency generator of millimeter waves known as a gyrotron traveling wave amplifier. In the example consided, wave amplification results from the interaction of a TE/sub 01/ waveguide mode with the fundamental cyclotron harmonic of an electron beam. The parameter optimization involves the determination of the point of maximum device efficiency as a function of beam density, beam energy, beam positioning, and external magnetic field for the output power required. An analytical linear theory and a numerical simulation code form the basis of theoretical calculations. As a result of the extensive survey in parameter space, the peak efficiency in the beam frame has been found to exceed 70 percent. This result has been applied to the specific design of a 35-GHz amplifier with output power ~340 kW, a power gain of 2 dB/cm, and a laboratory frame efficiency of 51 percent.     

A low-noise cryogenically-cooled 8–12 GHz HEMT Amplifier for future space applications

A two-stage 8–12 GHz (X-band) cryogenically-cooled Low-Noise Amplifier (LNA) has been developed with a commercial pseudomorphic HEMT on AsGa substrate. In a first step, different commercial transistors have been fully characterized from 300 K to 20 K using a new method to measure the four noise parameters. Preliminary results have allowed the selection of the best device. This enabled the design of the two-stage LNA with the help of a microwave CAD software. In a second step, the LNA has been characterized at 300 K, 30 K and 4 K. As the physical temperature decreased from 300 K to 30 K, the LNA exhibited an average gain increase of 2 dB and as much as a fourfold reduction of noise temperature. A noise figure of 22.5 K and a gain of 23 dB have been achieved at 30 K around 10 GHz. The noise temperature has been furthermore reduced to 20 K by cooling the amplifier at the liquid helium temperature (4.2 K). Different methods to measure the noise characteristics of the amplifier are widely developed in this paper.     

9.5-14.5 GHz GaAs HBT 1W MMIC with 55% peak power added efficiency

A fully matched, broadband, high efficiency MMIC power amplifier using AlGaAs/GaAs HBTs has been designed and tested. At 7 V collector bias, this HBT amplifier produced 31 dBm CW peak output power with 9 dB gain and 55% peak power-added efficiency in the 9.5-14.5 GHz band. To the authors' knowledge, this is the highest efficiency ever achieved from a broadband MMIC power amplifier     

8mm二次谐波回旋速调放大器的研究

对8mm高功率二次谐波回旋速调放大器进行了理论研究和优化设计,已研制出回旋速调放大器实验样管,并进行了热测实验,得到了如下结果:在中心频率为35GHz的情况下,得到的最大脉冲输出功率为180kW,效率为13%,增益为21dB;在电子束电压为58kV,电子束电流为25A的情况下,得到了150kW的输出功率,3dB带宽110MHz(0.3%).