A 0.4–1.2 GHz SiGe Cryogenic LNA for Readout of MKID Arrays

The design and characterization of a low noise amplifier optimized for the readout of microwave kinetic inductance detectors is described. The work is first motivated through a description of microwave kinetic inductance detectors and a discussion of the requirements for the low-noise amplifiers employed for readout of these devices. Next, the design of a two-stage silicon germanium cryogenic integrated circuit low noise amplifier is presented. The small-signal and large-signal characteristics of the fabricated amplifier are then measured. It is shown that, at a physical temperature of 16 K, the amplifier achieves a gain of greater than 30 dB and an average noise temperature of 3.3 K over the 0.4–1.2 GHz frequency band while dissipating less than 7 mW. Moreover, the wideband compression characteristics are measured it is found that the linearity of the amplifier is sufficient to support frequency domain multiplexed readout of more than 500 detectors.