Circuitry Approaches for Reducing of the Zero Level in Three-Stage CJFET Operational Amplifier

Circuit solutions CJFET three-stage OpAmp, in which non-ideal current mirrors (CMs) with a current transfer coefficient different from unity can be used in the intermediate stage, are considered. An OpAmp architecture in which the CM and all static-setting transistor references are replaced with identical JFET uncontrolled dynamic loads is proposed. Computer modeling in the CAD LTSpice (Analog Device, USA) and mathematical analysis of the proposed OpAmps made it possible to establish that OpAmp circuits are operable at negative temperatures (up to −197°C) and when exposed to a neutron flux up to 1014 n/cm2, have high values of open-loop gain (up to 100dB) and a small systematic component of the zero bias voltage due to the OpAmp circuitry.