Amplifier development for multiplexed cryogenic detectors

We make some considerations on the question of driving the cable from the cryogenic stage of refrigerators to the room temperature, in the case of multiplexed detector array systems where a high total Shannon information capacity is required. We have constructed large SQUID arrays for the purpose, some of which exhibit lower than 5 × 10⁻⁸ Φ₀ Hz^−1/2 flux noise at 4.2 K and do not require magnetic shielding in a typical laboratory environment. The option of using class-D amplifiers to reduce the cryogenic heat load is briefly reviewed.