Cryogenic ultra-low power dissipation operational amplifiers with GaAs JFETs

To realize a multipixel camera for astronomical observation, we developed cryogenic multi-channel readout systems using gallium arsenide junction field-effect transistor (GaAs JFET) integrated circuits (ICs). Based on our experience with these cryogenic ICs, we designed, manufactured, and demonstrated operational amplifiers requiring four power supplies and two voltage sources. The amplifiers operate at 4.2 K with an open-loop gain of 2000. The gain–bandwidth product can expect 400 kHz at a power dissipation of 6 μW. In performance evaluations, the input-referred voltage noise was 4 μV_rms/Hz^0.5 at 1 Hz and 30 nV_rms/Hz^0.5 at 10 kHz, respectively. The noise power spectrum density was of type 1/f and extended to 10 kHz.