Analogue operational amplifier comparator - uses output voltage when input is shorted to charge capacitor for offset voltage compensation

摘要

The offset voltage compensator, for an analogue comparator comprising an operational amplifier, also takes into account the temp. dependence of the offset voltage. The voltage present at the operational amplifier's (V1) output when its input is short circuited is used to charge a capacitor (C). The capacitor is connected via a resistor (R8) to that input (+) of the amplifier that permits the capacitor's voltage to compensate the offset voltage. The capacitor is charged by closing a switch (S2), which also simultaneously short circuits the amplifier inputs (+.-).