Cooling a low noise amplifier with a micromachined cryogenic cooler

The sensitivity of antenna systems increases with increasing active area, but decreases at higher noise figure of the low-noise amplifier (LNA). Cooling the LNA locally results in significant improvement in the gain and in lowering the noise figure of the LNA. Micromachined Joule-Thomson (JT) coolers can provide a cryogenic environment to the LNA. They are attractive because they have no cold moving parts and can be scaled down to match the size and the power consumption of LNAs. The performance of a LNA mounted on a JT microcooler with dimensions of 60.0 × 9.5 × 0.72 mm3 is reported in this paper. The microcooler is operated with nitrogen gas and the cold-end temperature is controlled at 115 K. The measured net cooling power of the microcooler is about 43 mW when the LNA is not operating. The power dissipation of the LNA is 26 mW, with a supply voltage of 2 V. At room temperature the noise figure of the LNA is 0.83 dB and the gain lies between 17.9 and 13.1 dB, in the frequency range of 0.65 and 1.05 GHz. Upon cooling to 115 K, the noise figure drops to 0.50 dB and the increase in gain varies in the range of 0.6–1.5 d

DC to 11GHz Fully Integrated GaAs Up Conversion Mixer

This paper describes the design and realization of a wide band single balanced fully integrated up-conversion mixer. The mixer has a RF bandwidth from 1 to 11GHz and an IF at 14 GHz, with an 1GHz bandwidth. This requires a LO frequency range from 15 to 25GHz. This single balanced mixer needs a single RF signal and a differential LO signals. The wide LO band prevents the use of a passive single to differential converter. We choose to integrate an active single to differential converter on chip. The output of the mixer core needs to be buffered. This to prevent unwanted mixing due to reflected signals from the IF output. To have enough buffering two single amplifiers are included

Decade Wide Bandwidth Integrated Very Low Noise Amplifier

This paper describes the design, realization and characterization of an integrated Low Noise Amplifier (LNA) with a bandwidth from 0.4 to 8 GHz. A very good noise figure is achieved in this frequency band. The design uses a source impedance of 150 ohm in the contrary to the standard of 50 ohm. The load impedance is 50 ohm. The use of a non-50 input source impedance creates new possibilities for the design of the power and noise matching circuitry. A combination of a good power and noise match can be achieved for a very broad band, with a minimum of components. This concept requires a non-standard antenna (source) output impedance (150 ohm), which is for most antenna principles easier to realize then 50 ohm [1]. The LNA will be part of an active antenna phased array system, which should operate from 0.2 to 2 GHz [2]

MMIC GaAs and InP Very Low Noise Amplifier Designs for the Next Generation Radio Telescopes

This paper describes different approaches to develop very low noise amplifiers for the next generation of radio telescopes. We do research to evaluate which process is most suitable to be used in the radio telescopes, we also make novel designs that will make the most of the present processes. To evaluate the processes we designed and measured comparable designs in the different processes. For this the focus has been mainly on the III/IV processes GaAs and InP. This paper will discus three different designs. Two comparable designs to evaluate the processes and the third is a differential design