Offset compensating circuit for operational amplifier
First Claim
1. An offset compensating circuit for an operational amplifier having two input terminals comprising:
- a reference voltage terminal connectable to a first input terminal;
comparing means connected to the output terminal of said operational amplifier and to said reference voltage terminal for comparing signal levels at both said terminals and generating a two-level signal indicating the result of said comparison;
counting means connected to said comparing means for generating a digital count at an output terminal in response to the state of said two-level signal; and
a digital-to-analog converter having an input terminal connected to the output terminal of said counting means and and having an output terminal connected to a second input terminal of said operational amplifier to supply said operational amplifier with an analog signal corresponding to said count to compensate for voltage offset in said operational amplifier.
1 Assignment
0 Petitions
Accused Products
Abstract
Disclosed is an offset compensating circuit for an operational amplifier having its noninverting input terminal supplied with a compensating voltage corresponding to its output voltage obtained when its inverting input terminal is grounded. This offset compensating circuit includes a comparator connected to the output terminal of the operational amplifier and comparing the output voltage of the operational amplifier with a set voltage to deliver a binary signal corresponding to the result of such comparison, a pulse generator, an up-down counter for counting output pulses from the pulse generator in a count direction in accordance with the level of the output signal of the comparator, and a D/A converter for supplying the noninverting input terminal of the operational amplifier with a voltage corresponding to the count output of the up-down counter.
33 Citations
10 Claims
-
1. An offset compensating circuit for an operational amplifier having two input terminals comprising:
-
a reference voltage terminal connectable to a first input terminal; comparing means connected to the output terminal of said operational amplifier and to said reference voltage terminal for comparing signal levels at both said terminals and generating a two-level signal indicating the result of said comparison; counting means connected to said comparing means for generating a digital count at an output terminal in response to the state of said two-level signal; and a digital-to-analog converter having an input terminal connected to the output terminal of said counting means and and having an output terminal connected to a second input terminal of said operational amplifier to supply said operational amplifier with an analog signal corresponding to said count to compensate for voltage offset in said operational amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. An offset compensating circuit comprising:
-
a reference voltage terminal; an operational amplifier having two input terminals, a first one of which is connected to receive a signal from said reference voltage terminals; comparing means having a first input terminal connected with the output terminal of said operational amplifier, having a second input connected to a comparison signal, said comparing means generating a two-level signal at an output terminal; computing means connected to the output terminal of said comparing means to deliver first and second digital signals at first and second output terminals, respectively, in response to the state of said two-level signal; a first D/A converter connected between the first output terminal of said computing means and the second input terminal of said comparing means to supply the second input terminal of said comparing means with said comparison signal corresponding to an output signal of said computing means; and a second D/A converter connected between the second output terminal of said computing means and a second input terminal of said operational amplifier to supply said operational amplifier with an analog signal corresponding to a second output signal of said computing means to compensate for voltage offset in said operational amplifier.
-
Specification