Cryogenic noise performance of HEMTs and MESFETs between 300 and700 MHz

The authors present the noise performance of amplifiers using HEMTs and MESFETs at room temperature and cryogenic temperatures, in the frequency range 300-700 MHz. Results demonstrate that these microwave devices can be applied at frequencies down to at least 300 MHz, giving amplifier noise temperatures below 2 K at 20 K ambient temperature     

Cryogenic characteristics of wide-band pseudomorphic HEMT MMIClow-noise amplifiers

Two wideband (8-18-GHz) single-stage MMIC (monolithic microwave integrated circuit) low-noise amplifiers (LNAs) using 0.2-μm T-gate InGaAs pseudomorphic HEMT (high-electron-mobility transistor) technology, designed and fabricated for room temperature operation, were evaluated and compared at cryogenic temperatures below 20 K. One is a balanced design using 3-dB Lange couplers, and the other is a feedback design using a series RLC parallel feedback network. The gain flatness over the 8-18-GHz frequency band was maintained for both amplifiers at room and cyrogenic temperatures, indicating that the topology for wideband designs is insensitive to temperature of operation. As the physical temperature decreased from 297 K to below 20 K, the balanced LNA exhibited an average gain increase of 2 dB and as much as an eightfold reduction of noise temperature to 20 K, while the feedback LNA exhibited an average gain increase of less than 1 dB and an average foufold reduction of noise temperature to 50 K. The negative feedback network of the feedback LNA resulted in less gain increase and less noise temperature reduction at cryogenic temperatures     

Gallium-arsenide E- and D-MESFET device noise characteristicsoperated at cryogenic temperatures with ultralow drain current

The low-frequency noise characteristics of GaAs MESFETs operating at very low power and at cryogenic temperatures of 77 and 10 K as well as at room temperature are discussed. A self-aligned gate and a buried p-layer were incorporated to maximize device gain and minimize low-frequency noise. Measurements at 77 K show a noise voltage spectral density of 1.0-2.0 μV/√Hz at 1.0 Hz (referred to the transistor input) with a drain current of 1.0 μA     

All Solid-State Low-Noise Receivers for 210-240 GHz

Low-noise all solid-state receiver systems for room temperature and cryogenic operation between 210 and 240 GHz are described. The receivers incorporate a single-ended fixed tuned Schottky barrier diode mixer, a frequency-tripled Gunn source as local oscillator and a GaAsFET IF amplifier. Single sideband receiver noise temperatures are typically 1300 K (7.39-dB noise figure) for a room temperature system and 470 K (4.18-dB noise figure) for a cryogenically cooled receiver operating at 20 K.     

Microwave and noise performance of SiGe BiCMOS HBT under cryogenic temperatures

In this letter, the microwave and noise performance of SiGe heterojunction bipolar transistors (HBTs) has been characterized when cooling down the temperature. It was found that SiGe HBTs (fabricated in the framework of BiCMOS process) exhibit a maximum oscillation frequency f/sub max/ of about 292 GHz at 78 K, which represents an increase of about 30% with the value measured at room temperature. The noise performance has also been characterized at cryogenic temperatures, using an original de-embedding approach. Then, using the Hawkin's noise model in conjunction with an accurate small signal equivalent extraction, the four noise parameters have been estimated. The noise figure with a 50 /spl Omega/ source impedance was measured to be equal to 1.5 dB at 40 GHz at 78 K, which is one of the lowest value reported for BiCMOS SiGe HBT in the millimeter-wave range.     

A 350GHz Radial-Probe SIS Mixer for Astronomical Imaging Arrays

We have developed a 330-370GHz SIS mixer for small-format, heterodyne, astronomical imaging arrays. Fixed-tuned broadband operation is achieved by means of a superconducting radial waveguide probe. A horn-reflector antenna provides high-efficiency optical coupling. Using a variable-temperature cryogenic noise source, we measured a DSB system noise temperature of 32±1K. The mixer contributes 3±3K, supporting the theoretically-predicted result that the noise temperature of a DSB mixer can be less than hω/2κ (8.6K)     

Low-Noise Cooled GASFET Amplifiers

Measurements of the noise characteristics of a variety of gallium-arsenide field-effect transistors at a frequency of 5 GHz and temperatures of 300 K to 20 K are presented. For one transistor type detailed measurements of dc parameters, small-signal parameters, and all noise parameters (T/sub min/, R/sub opt/, X/sub opt/ g/sub n/) are made over this temperature range. The results are compared with the theory of Pucel, Haus and Statz modified to include the temperature variation. Several low-noise ampifiers are described including one with a noise temperature of 20 K over a 500-MHz bandwidth. A theoretical analysis of the thermal conduction at cryogenic temperatures in a typical packaged transistor is included.     

Terahertz detection by GaN/AlGaN transistors

Detection of subterahertz and terahertz radiation by high electron mobility GaN/AlGaN transistors in the 0.2-2.5 THz frequency range (much higher than the cutoff frequency of the transistors) is reported. Experiments were performed in the temperature range 4-300 K. For the lowest temperatures, a resonant response was observed. The resonances were interpreted as plasma wave excitations in gated two-dimensional electron gas. Non-resonant detection was observed at temperatures above 100 K. Estimates for noise equivalent power show that these transistors can be used as efficient detectors of terahertz radiation at cryogenic and room temperatures     

一种透射式低温光学系统的设计与验证

由于能够减小系统自身的热噪声和提高系统信噪比,低温光学是实现高灵敏度红外探测的必要手段。提出了一种将脉冲管制冷机用作冷源的透射式低温光学系统。这种新型低温光学系统可用于体积和重量受限而又需要进行高灵敏度红外探测的场合。从光学设计、光机结构设计和内部热噪声分析等方面说明了透射式低温光学系统的设计过程。搭建了用于对脉冲管制冷机冷却光学系统的可行性进行验证的试验系统,并从系统内部热噪声的角度对低温光学的有效性进行了验证。实验结果表明,经过3 h,透镜温度由300 K降至设计温度150 K,继续降温则可达到最低温度105 K。测试过程中,透镜保持完好,验证了将脉冲管制冷机用作冷源的可行性。用黑体和320×256元碲镉汞探测器对光学系统自身的热噪声进行了测试。结果表明,当光学系统的温度从300 K降至215 K时,其自身热辐射减少了75%。这与理论分析结果一致,验证了低温光学降噪的有效性。     

High-frequency noise of InyGa1?yAs/AlxGa1?xAs MODFETs and comparison to GaAs/AlxGa1?xAs MODFETs

Noise parameter measurements for recently developed 1 ?m gate InyGa1?yAs/Al0.15Ga0.85As MODFETs have been performed at 8 GHz at room and cryogenic temperatures. Owing to the relatively small Cgs/?gm ratio in these devices compared to identical conventional GaAs/AlGaAs MODFETs, both room- and cryogenic temperature noise figures have been reduced. In addition, the light sensitivity and drift in noise figure at cryogenic temperatures observed in conventional GaAs/AlGaAs MODFETs have been sub stantially reduced.     

Characterization of a 680–760 GHz SIS waveguide mixer

A heterodyne waveguide receiver employing 1 µm² Nb superconducting tunnel junctions with on chip integrated tuning structures is characterized from 680–760 GHz. Several different types of integrated tuning structures are investigated. Lowest DSB receiver noise temperatures of 310 K at 709 GHz and 400 K at 720 GHz are measured. Analysis of the data shows that the loss of the superconducting tuning structures has a major influence on the overall receiver performance. A 25% reduction in receiver noise temperature is observed if the mixer is cooled from 4.2 K to 2 K, which we attribute to the reduced loss of the superconducting microstrip lines at lower temperatures. The calculated performance of the different tuning structures is shown to be in good agreement with the actual receiver noise measurements.     

Cryogenic wide-band ultra-low-noise IF amplifiers operating at ultra-low DC power

This paper describes cryogenic broad-band amplifiers with very low power consumption and very low noise for the 4-8-GHz frequency range. At room temperature, the two-stage InP-based amplifier has a gain of 27 dB and a noise temperature of 31 K with a power consumption of 14.4 mW per stage, including bias circuitry. When cooled to 15 K, an input noise temperature of 1.4 K is obtained at 5.7 mW per stage. At 0.51 mW per stage, the input noise increases to 2.4 K. The noise measurements have been repeated at different laboratories using different methods and are found consistent.     

极端低温下硅基器件和电路特性研究进展

讨论了在极端低温下,硅基半导体在器件级和电路级特性的研究进展。在器件级,分析了极端低温下体硅器件和SOI器件常规电学特性的异常变化,讨论了一些只在极端低温下出现的特殊效应,如载流子冻结效应,阐述了极端低温下提取器件参数的方法。在电路级,分析了极端低温下反相器、CMOS运算放大器和DRAM的性能相对于常温下的变化,对比了极端低温下不同结构的电路在性能和稳定性方面的差异。最后,介绍了国内外相关研究领域的现状,并提出了未来极端低温微电子技术的发展方向。     

Improved performance of a cooled photoreceiver for high speedcommunication

An alternative method of improving photoreceiver sensitivity in a high-bit-rate optical transmission system is described. HEMTs have recently become commercially available and are known to generate mainly thermal noise and to exhibit transconductance enhancement at cryogenic temperatures. This suggests that a cooled photoreceiver with a HEMT in the first stage of the front-end amplifier could have an improved sensitivity with respect to that of room temperature operation. The DC transconductance variation between room temperature and 40 K for HEMTs of various technologies is presented. The signal-to-noise (S/N) ratios of a photoreceiver with a first-stage HEMT working at room temperature and 45 K are compared. The S/N improvement is currently about 4 dB (optical). It is found that HEMT noise generated in the frequency range considered does not seem to be of pure thermal origin. The results confirm that the proportion of MOCVD (metalorganic chemical vapor deposited) HEMTs exhibiting electrical characteristic degradation at low temperature is far less for MBE (molecular-beam epitaxial) HEMTs     

Cryogenic performance of a high-speed GaInAs/InP p-i-n photodiode

The cryogenic performance of a high-speed GaInAs/InP p-i-n photodiode, with graded bandgap layers at the heterostructure interfaces, was investigated for the first time. DC measurements show that the dark current of the diode decreases sharply as the temperature decreases from 300 to 200 K. A factor of 1000 in dark current reduction was found for this photodiode, when it was cooled from room temperature to about 150 K. Similar modulation bandwidths were found for this device for temperatures between 9 and 300 K, with a bandwidth greater than 20 GHz. No degradation was found in performance at cryogenic temperature compared to room temperature. This enables direct integration of high-speed photodiodes with superconductive and other cryogenic electronics     

Modeling of noise parameters of MESFETs and MODFETs and theirfrequency and temperature dependence

A simple noise model of a microwave MESFET (MODFET, HEMT, etc.) is described and verified at room and cryogenic temperatures. Closed-form expressions for the minimum noise temperature, the optimum generator impedance, the noise conductance, and the generator-impedance-minimizing noise measure are given in terms of the frequency, the elements of a FET equivalent circuit, and the equivalent temperatures of intrinsic gate resistance and drain conductance to be determined from noise measurements. These equivalent temperatures are demonstrated in the case of a Fujitsu FHR01FH MODFET to be independent of frequency in the frequency range in which 1/f noise is negligible. Thus, the model allows prediction of noise parameters for a broad frequency range from a single frequency noise parameter measurement. The relationships between this approach and other relevant studies are established     

Noise performance at cryogenic temperatures at AlGaAs/InGaAs HEMT'swith 0.15-μm T-shaped WSix gates

T-shaped 0.15-μm WSi_x gate HEMTs have been fabricated on AlGaAs/InGaAs MBE wafers. Their S-parameters, output noise spectral density P_no, and noise temperatures T _e at cryogenic temperatures, were measured. The current gain cutoff frequency f_T increases from 61 GHz at 295 K to 87 GHz at 90 K. P_no and T_e measurements indicate that the hot-electron effect is noticeable at low temperatures at high drain current. At 30 GHz, the noise temperature is 19±3 K with an associated gain of 10.4 dB at the physical temperature of 20 K. The results demonstrate the great potential of AlGaAs/InGaAs HEMTs for low-temperature applications     

Ultra-low-noise cryogenic high-electron-mobility transistors

Quarter-micrometer gate-length high-electron-mobility transistors (HEMTs) for cryogenic low-noise application with very low light sensitivity have been developed. At room temperature, these exhibit a noise figure of 0.4 dB with associated gain of 15 dB at 8 GHz. At a temperature of 12.5 K the minimum noise temperature of 5.3±1.5 K has been measured at 8.5 GHz, which is the best noise performance observed to date for any microwave transistors. The results clearly demonstrate the potential for low-temperature low-noise applications     

4 K低温辐射计的吸收腔吸收率测试技术研究

为了实现低温辐射计工作温度4 K条件下吸收腔吸收率的测量,研究了变温条件下吸收腔吸收率的测量方法。通过在低温辐射计布儒斯特窗口前设计反射监测组件,并控制低温辐射计工作在10?6 Pa的真空环境下,调节低温辐射计制冷温度,分别测量室温条件和不同温度条件下低温辐射计吸收腔在632.8 nm处的反射信号,结合利用传统积分球法在室温条件下低温辐射计吸收腔632.8 nm处反射率的测量结果,通过计算可精确得到不同温度条件下低温辐射计吸收腔的吸收率。实验测量吸收腔在室温条件和4 K温度条件下的吸收率,分别为0.99976和0.99971,对4 K条件下低温辐射计吸收腔吸收率的测量不确定度进行评定,得到的结果显示其相对扩展不确定度为0.005%（k=2）。