INTEGRATION CIRCUIT

摘要

PURPOSE:To eliminate substantially the offset effect of an operational amplifier by supplying the variable microvoltage to a non-inverted input terminal of the operational amplifier constituting an integration circuit when the input voltage is set at an earth potential. CONSTITUTION:The variable analog voltage Vos corresponding to a digital signal is supplied to a non-inverted input terminal (+) of an operational amplifier OP1 through a D/A converting circuit which receives the digital signal produced by a counter circuit CON. Then the integration voltage Vo is delivered from the output terminal of the amplifier OP1, and the polarity of the voltage Vo is decided by a voltage comparator VC1. The positive inverted output signal delivered from the circuit VC1 is fetched to a latch circuit FF and used as a control signal of a gate circuit G which supplies the clock signal phi to the circuit CON. This control signal controls the counter operation so that the integration output is set at ''0'' when the input voltage is set at ''0''. This eliminates substantially the offset effect of the amplifier OP1.