Operational amplifier circuit
AssigneeSeiko Instruments Inc.
InventorTsutomu TOMIOKA
Life of this patent
Estimating the term…
Abstract
Provided is an operational amplifier circuit having a high tolerance for clock phase difference fluctuations. An FIR filter is used to add an input signal of the FIR filter to a signal obtained by delaying the input signal of the FIR filter. In this manner, chopper noise can be removed. Thus, the operational amplifier circuit may have a high tolerance for clock phase difference fluctuations regardless of the phase difference between clocks for controlling a chopper circuit and the FIR filter.
Claims6
An operational amplifier circuit for amplifying a difference between signals input to input terminals and outputting the amplified difference from an output terminal, the operational amplifier circuit comprising:
- a first amplifier stage connected to the input terminals of the operational amplifier circuit;
- a first chopper circuit that is connected to the input terminals of the operational amplifier circuit and controlled by a first clock, the first chopper circuit having a function of modulating input signals;
- a second amplifier stage connected to output terminals of the first chopper circuit;
- a second chopper circuit that is connected to output terminals of the second amplifier stage and controlled by the first clock, the second chopper circuit having a function of demodulating input signals;
- an integrating circuit that is connected to output terminals of the second chopper circuit and has a function of integrating input signals;
- an FIR filter connected to output terminals of the integrating circuit;
- a third amplifier stage connected to output terminals of the FIR filter;
- and
- a fourth amplifier stage that is connected to an output terminal of the first amplifier stage and an output terminal of the third amplifier stage, and has an output terminal connected to the output terminal of the operational amplifier circuit.
Dependencies are inferred from the claim text.