Cryogenic ultra-low power dissipation operational amplifiers with GaAs JFETs

• We developed a cryogenic OP-Amp and demonstrated its operation at 4.2 K.
• Power dissipation of this OP-Amp was 6 μW.
• Open loop gain was 2000 and gain–bandwidth product was 400 kHz.
• This OP-Amp should have low input leakage current (<10 atto A).
• This OP-Amp should be workable even at 0.3 K.

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 μVrms/Hz0.5 at 1 Hz and 30 nVrms/Hz0.5 at 10 kHz, respectively. The noise power spectrum density was of type 1/f and extended to 10 kHz.