The cable capacitance in cryogenic and high vacuum applications of quartz tuning forks imposes severe constraints on the bandwidth and noise performance of the measurement. We present a single stage low noise transimpedance amplifier with a bandwidth exceeding 1 MHz and provide an in-depth analysis of the dependence of the amplifier parameters on the cable capacitance.

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We have constructed a dc-coupled differential amplifier capable of operating in the 4.2 K – 300 K temperature range. The amplifier can be operated at high-bias setting, where it dissipates 5 mW, has noise temperature TN < 0.8 K at 4 k source resistance and >40 MHz bandwidth at 4.2 K bath temperature. The bias setting can be adjusted: at our lowest tested setting the amplifier dissipates <100 W,...

We have developed an ultra-low noise 94 GHz MMIC amplifier using InGaAsfInAlAsfInP transistor technology. The MMIC designs incorporate a single transistor stage with input and output matching networks as well as gate and drain bias networks. Two MMICs have been incorporated into a single housing providing 10 dB of gain. At room temperature, the integrated amplifier has a measured noise of 365 K...

Aperture phased arrays operating up to 1 GHz are highly flexible collector systems, uniquely capable of performing an HI survey of a billion galaxies and observations of the Epoch of Reionisation, two of the Key Science Programmes for the Square Kilometer Array, SKA. Such high performance arrays are only becoming feasible in the timescales of the SKA due to technological advances in array desig...