DIFFERENTIAL AMPLIFIER Russian patent published in 1996 - IPC

FIELD: electric measurement technology; digital multimeters for scaling input signal. SUBSTANCE: automatic correction of bias voltage across two-position switch 14, switch 15, capacitor 10, and current-limiting resistor 11 of differential amplifier, that has differential input stage built around field-effect transistors 1, 2 with source resistors 3, 4, correcting resistors 5, third and fourth field-effect transistors 6, 7, takes place without influencing its temperature stability. Closing inputs of differential amplifier and switch 15 builds up voltage across capacitor 10 that corresponds to differential stage bias voltage that changes drain currents of field-effect transistors 6, 7 and resistor 5 carries correcting current causing voltage drop of polarity other than that of differential stage bias voltage; drain currents of field-effect transistors 1 and 2 do not change in the process. EFFECT: improved conversion accuracy and temperature stability of differential amplifier bias voltage. 1 dwg