Temperature-compensated analogue multiplier

The letter describes a 4-quadrant analogue multiplier which uses a field-effect transistor as a voltage-variable conductance in a differential-amplifier circuit configuration. Feedback is applied to the gate of the f.e.t. to linearise the IDS/VDS characteristic. A second matched f.e.t. is used to compensate for the changes in temperature, resulting in an accuracy of within 1% over a 50 deg. C temperature range.