Improvements in or relating to integrated circuits.

摘要

@ A high impedance is implemented in the input bias path of an integrated instrumentation amplifier by a normally on transistor switch. A signal from the output of the amplifier is used to turn the switch off to provide the requisite high impedance. Otherwise, the switch is on to provide low impedance for proper biasing. The circuit is adapted for encoded input signals such as occur in capacitive coupled credit card encoding circuits.