Parametric amplifier with thermoelectric refrigeration

The noise figure of a variable-capacitance parametric amplifier can be greatly improved by refrigerating the diode. A thermoelectric refrigerator can be used for this purpose without losing the advantage of system simplicity. A two-stage thermoelectric refrigerator has been built into a 6-Gc parametric amplifier. With no load this refrigerator has produced a temperature difference of 101°C below room temperature. In the amplifier it cooled the diode to 213°K. The effective noise temperature of the amplifier was reduced from 170°K when the GaAs diode was at room temperature to 108°K when the diode was cooled to 213°K. The design, construction and characteristics of the amplifier and the thermoelectric refrigerator are described.     

Precision measurement method for cryogenic amplifier noise temperatures below 5 K

We report precision measurements of the effective input noise temperature of a cryogenic (liquid-helium temperature) monolithic-microwave integrated-circuit amplifier at the amplifier reference planes within the cryostat. A method is given for characterizing and removing the effect of the transmission lines between the amplifier reference planes and the input and output connectors of the cryostat. In conjunction with careful noise measurements, this method enables us to measure amplifier noise temperatures below 5 K with an uncertainty of 0.3 K. The particular amplifier that was measured exhibits a noise temperature below 5.5 K from 1 to 11 GHz, attaining a minimum value of 2.3 K/spl plusmn/0.3 K at 7 GHz. This corresponds to a noise figure of 0.034 dB/spl plusmn/0.004 dB. The measured amplifier gain is between 33.4 dB/spl plusmn/0.3 dB and 35.8 dB/spl plusmn/0.3 dB over the 1-12-GHz range.     

A low-noise 1.2–1.8 GHz cooled GaAs FET amplifier

A low-noise 1.2–1.8 GHz cooled GaAs FET amplifier with mixer bias circuit is reported. The amplifier noise temperature obtained at an ambient temperature of 20 K in the frequency range of 1.2–1.7 GHz is 10K. The lowest noise temperature is 4K. The gain is about 30 dB. An automatic measuring instrument for noise temperature was designed. The noise effect of the input cable and the error analysis of the total measurement were made. The total measurement error is 2 K.     

Cryogenically Cooled GaAs FET Amplifier with a Noise Temperature Under 70 K at 5.0 GHz (Short Papers)

A 4.5-5.0-GHz gallium arsenide field-effect transistor (GaAs FET) amplifier cryogenically cooled to approximately 70 K is described. A noise temperature of under 70 K is achieved over the hand. Power gain for the two-stage amplifier is 20 dB. A noise analysis is performed to predict noise-temperature dependence on the temperature of the amplifier.     

Maximum Bandwidth Performance of Non- degenerate Parametric Amplifier with Single-Tuned Idler Circuit

The single-tuned bandwidth and limiting flat bandwidth of a nondegenerate reflection-type diode parametric amplifier is calculated. The amplifier has a broad-banding filter structure in the signal circuit and a single-tuned idler circuit. An experimental low-noise, wide-band Z-band amplifier is described, and measurement results are presented. The amplifier has a triple-tuned signal circuit and a single-tuned idler circuit and is pumped at 11.3 Gc. A nearly flat bandwidth of 23 per cent at 7 db gain and an effective input noise temperature of 70/spl deg/K at room temperature ambient and of 29/spl deg/K at liquid nitrogen (77/spl deg/K) ambient has been obtained.     

Low-noise 10.7 GHz cooled GaAs FET amplifier

A three-stage gallium-arsenide field-effect transistor amplifier giving a noise temperature of 29 K (0.4 dB noise figure) at a physical temperature of 13 K is described. The amplifier utilises a novel modular construction with coaxial air-lines, sliding ?/4 transformers, and packaged NE13783 and MGF1403 FETs. Noise parameters of these devices at 300 K and 13 K are reported.     

Low-noise room-temperature parametric amplifier

The use of the phase-locked degenerate parametric amplifier in digitally modulated communication systems has been proposed. In the letter, we report successful operation of this device as an amplifier for high-speed phase-shift-keyed signals. Noise temperature measured on a 4 GHz device by a system (error-rate) measurement and by a Y factor method give a noise temperature of 46 K, including 11 deg K from the circulator, with the amplifier at room temperature.     

Cryogenic GaAs FET amplifier

An extremely low noise, cryogenic, gallium arsenide field-effect-transistor amplifier has been developed for the frequency range 3.7 to 4.2 GHz. The amplifier has an average noise temperature of 25 K, with an associated gain of 21 dB, when cooled to a physical temperature of 77 K.     

Limitations on the noise figure of microwave amplifiers of the beam type

A general model is developed for microwave amplifiers of the beam type based on the usual assumptions of a small signal, one-dimensional, single velocity flow of the electrons in the beam. The model includes arbitrary noise smoothing schemes and all amplifiers whose input and output structures have no direct rf connection; the rf coupling is provided solely by means of the modulated electron beam. A klystron, a space-charge wave amplifier, and a traveling-wave tube with a severed helix (or a helix with strong localized attenuation) are all special cases of this model. It is shown that the minimum noise figure of such an amplifier is of the form Fmin=1+2Π/kT|K| [S(z0,w)- K/|K| Π(z0,w) where S(z0,w) and Π(z0,w) are parameters of the beam noise expressed at a cross section z0slightly beyond the potential minimum in the electron gun, k is Boltzmann's constant, T is the temperature of the circuit, and K is a constant dependent upon the particular structures used. The dependence of K upon the microwave structures employed is discussed under restrictive assumptions about the loss in the rf structure of the amplifier. Two cases are possible. In the first case, the minimum possible value of K is unity. In the second, K is less than unity. It is shown, however, that in the latter case the available gain, G0, of the amplifier is given by G0=1/1-K     

Constant-output-frequency, octave tuning range backward-wave parametric amplifier

This paper describes a varactor diode backward-wave parametric amplifier (BWPA) which operates in a new mode that yields a constant-output frequency as the amplification frequency is electronically turned over an octave signal tuning range. A theoretical discussion on the design considerations is presented and applied to the construction of an LF model (1.5-3.3 Mc). Experimental data on the important amplifier characteristics are given and shown to correlate well with theory. The amplifier yields stable gains in excess of 20 db over a greater-than-octave tuning range, and the output frequency (which is taken at the idler) has less than a ± 1.6 per cent variation over the octave band. The over-all effective receiver input-noise temperatures were measured and agreed well with theory, being about 160°K at the LF end of the band and increasing to 300°K at the HF end.     

Broadband cryogenic parametric amplifier operating at 11.6 GHz

A machine-cooled cryogenic parametric amplifier that operates at 20 K is described. The 2-stage amplifier has a 0.5 dB bandwidth of 600 MHz at 20 dB gain and an effective input noise temperature in the range 47?51 K over the frequency band of 11.3 to 11.9 GHz     

Externally pumped millimeter-wave Josephson-junction parametric amplifier

A unified theory of the singly and doubly degenerate Josephson-junction parametric amplifier is presented. Experiments with single junctions on both amplifier modes at frequencies 10, 35, and 70 GHz are discussed. Low-noise temperature (∼100 K, single sideband (SSB)) and reasonable gain (∼8 dB) were obtained at 35 GHz in the singly degenerate mode. On the basis of the theory and experiments, a general procedure for optimizing junction parameters is discussed and illustrated by the specific design of a 100-GHz amplifier.     

CO2laser preamplifier capabilities for low-level 10.6-µm direct-detection receivers

We examine the potential of CO2laser preamplifiers for sensitivity enhancement in low-level, direct-detection 10.6-μm receivers. For the condition in which a gain-dependent competition exists between the background noise and amplifier spontaneous emission noise (assuming negligible thermal noise), the analysis predicts an optimum useful SNR enhancement of only 6 dB for a blackbody background field of 300 K and 4.1 dB for a background of 260 K, when the amplifier gain bandwidth perp-line is 100 MHz and the infrared (IR) filter bandwidth is 0.10 μm. Based on preselected choice of gain and bandwidth, a two-stage, water-cooled, flowing-gas amplifier of optimized design was constructed. A maximum gain of 3.12 dB was attained forP(20)with a He : CO2: N2mixture of 5.0 : 1.0 : 0.6 at a coolant temperature of 285 K and a slow gas refresh rate of 0.2 volumes/s. Using a fast-flow system with 12-volume/s refresh rate, we measured an amplifier gain of 3.9 dB, close to the design estimate of 4.1 dB. With a calibrated HgCdTe detector,f/4cold shield, and narrow-band (0.25 μm) cold filter, a spontaneous emission flux density ofsim 1.0 times 10^{14}photons/ cm². s was measured at the 3.12-dB gain level, in close agreement with the theoretical estimate. Excess noise resulting from amplifier discharge was undetectable above the basic detector noise.     

一种带宽为3.8GHz，增益步长为0.1dB的可编程增益放大器

A broadband programmable gain amplifier（PGA） with a small gain step and low gain error has been designed in 0.13 m CMOS technology. The PGA was implemented with open-loop architecture to provide wide bandwidth. A two-stage gain control method, which consists of a resistor ladder attenuator and an active fine gain control stage, provides the small gain step. A look-up table based gain control method is introduced in the fine gain control stage to lower the gain error.The proposedPGAshows a decibel-linear variable gainfrom4 to20 dB with a gain step of 0.1 dB and a gain error less than˙0.05 dB. The 3-dB bandwidth and maximum IIP3 are 3.8 GHz and 17 dBm, respectively.     

低噪声1.21.8GHz致冷FET放大器

本文介绍了低噪声1.21.8 GHz致冷FET放大器的研制工作。在20K环境温度下,带宽1.21.7GHz范围内,放大器噪声温度低于10K,最佳为4K。增益约30dB。设计了一个噪声温度自动测试系统。另外对输入电缆的噪声和总测量误差作了分析。测试总误差为2K。     

A multigigahertz Josephson-semiconductor interface circuit using77-K differential monolithic HEMT amplifier and 4.2-K JJ high-voltagedriver for superconductor-semiconductor electronic hybrid systems

We proposed and successfully demonstrated a high-speed Josephson IC to semiconductor IC output interface circuit combining a high electron mobility transistor (HEMT) amplifier and Josephson high-voltage drivers successfully. We developed a 0.5-μm gate 77-K wide-band analog monolithic HEMT amplifier for the interface. The HEMT device consisted of InGaP/InGaAs materials stable even at 77 K. The amplifier has a differential amplifier as a first stage to cancel out ground-level fluctuations in the Josephson IC and showed a voltage gain of 23 dB and ~3-dB frequency of 8 GHz. A 0.63-V_p-p output was obtained from a 5-GHz, 30-mV_p-p complementary input signal. We succeeded in transfer ring a voltage signal from 10-stack Josephson high-voltage drivers to a 50-Ω system at room temperature with 0.7-V_p-p amplitude at 300-MHz clock using the HEMT amplifier     

100-GHz cooled amplifier residual PM and AM noise measurements, noise figure, and jitter calculations

We report the first definitive PM and AM noise measurements at 100 GHz of indium phosphide (InP) amplifiers operating at 5 K, 77 K, and room temperature. Amplifier gain ranged from +7 to +30 dB, depending on input RF power levels and operating bias current and gate voltages. The measurement system, calibration procedure, and amplifier configuration are described along with strategies for reducing the measurement system noise floor in order to accurately make these measurements. We compute amplifier noise figure with an ideal oscillator signal applied and, based on the PM noise measurements, obtain NF=0.8 dB, or a noise temperature of 59 K. Measurement uncertainty is estimated at /spl plusmn/0.3 dB. Results show that the use of the amplifier with an ideal 100-GHz reference oscillator would set a lower limit on rms clock jitter of 44.2 fs in a 20-ps sampling interval if the power into the amplifier were -31.6 dBm. For comparison, clock jitter is 16 fs with a commercial room-temperature amplifier operating in saturation with an input power of -6.4 dBm.     

First steps towards a high-Tc squid amplifier

A high-T_c DC SQUID amplifier has been prepared and tested. The principle of operation of the amplifier was first proved by using low-T_c Nb-Al₂O₃-Nb SQUIDs with integrated Nb input coils. A flux gain factor of about 20 was demonstrated at 4.2 K with the low-T_c SQUIDs. The operation of the high-T_c SQUID amplifier was demonstrated by using step edge and/or bicrystal DC SQUIDs. The input coils of the amplifier were wire wound copper coils. A flux gain of about 8 has been measured at 77 K. A flip chip arrangement with a thin film coil has also been tried. In this case, one input coil was a one turn high T_c superconducting strip. The second coil consisted of a 22-turn high-T_c superconducting stripline with a gold strip crossover. The measurements showed a high contact resistance between Au and YBa₂Cu₃O_7−δ which was detrimental for a proper operation of the amplifier.     

32-GHz cryogenically cooled HEMT low-noise amplifiers

The cryogenic noise temperature performances of a two-stage and a three-stage 32-GHz HEMT (high-electron-mobility transistor) amplifier were evaluated. The amplifiers utilize quarter-micrometer conventional AlGaAs/GaAs HEMT devices, hybrid matching input and output microstrip circuits, and a cryogenically stable DC biasing network. The noise temperature measurements were performed in the frequency range of 31 to 33 GHz over a physical temperature range of 300 to 12 K. Across the measurement band, the amplifiers displayed a broadband response, and the noise temperature was observed to decrease by a factor of ten in cooling from 300 to 15 K. The lowest noise temperature measured for the two-stage amplifier at 32 GHz was 35 K with an associated gain of 16.5 dB, while for the three-stage amplifier it was 39 K with an associated gain of 26 dB. It was further observed that both amplifiers were insensitive to light