Single-stage, low-noise, low temp. amplifier - has magnetoresistive amplifier coupling coil linked in parallel, or series, to two-contact SQUIDs

摘要

The highly sensitive amplifier consists of DC, or DC voltage fed, two-contact SQUID, behind which is linked a magnetoresistive amplifier with an input coupling coil. The latter is coupled in parallel or in series to the two contact SQUID. Pref. the coil has a definite resistance. A resistor in a further low temp. branch may be variable. For this purpose are used superconductive switches with different critical currents. Thermal, optical, or magnetic effects may be also used. Proportional or integral current amplification may be used. USE/ADVANTAGE - For measuring small currents, voltages or magnetic fields, without feedback and noise suppression circuits.