Low input bias current chopping switch circuit and method

a chopping switch and low input bias current technology, applied in the direction of pulse automatic control, dc isolation amplifier, pulse technique, etc., can solve the problem of not much design flexibility for adjusting these two variables in order to meet certain design requirements, and the prior art chopper stabilization circuitry is associated with an increased input bias current and other problems, to achieve the effect of low output ripple noise and low input bias curren
US20110316621A1Active Publication Date: 2011-12-29TEXAS INSTR INC
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
TEXAS INSTR INC
Publication Date
2011-12-29

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Abstract

A chopper-stabilized circuit (1) includes pre-chopping circuitry (26) for chopping an input signal (Vin) at a first frequency to generate a first signal. Input chopping circuitry (9) chops the first signal at a second frequency substantially greater than the first frequency to produce a second signal. The first frequency is a sub-harmonic of the second frequency. Post-chopping circuitry (30) chops the second chopped signal at the first frequency to produce a third signal that is applied to an input of a signal conditioning circuit (2). The output chopping circuitry (10) chops an output of the signal conditioning circuit at the second frequency to generate a fourth signal. The fourth signal is filtered.
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Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates generally to chopper-stabilized operational amplifiers. The invention also relates to chopper-stabilized operational amplifiers which include notch filters to reduce output ripple voltage due to the chopping signals. The invention relates more particularly to improvements which substantially reduce input bias current without necessarily decreasing chopping clock voltage level levels, without causing increased chopping-clock-induced ripple voltages, and / or without the need to increase notch filter capacitor size.

[0002] Chopper-stabilized operational amplifiers used as stand alone operational amplifiers provide excellent offset voltage and offset voltage drift performance without the need for trimming of components to reduce offset and drift. This means that in addition to good DC performance, chopper-stabilized operational amplifiers also have advantages of reduced integrated circuit die size and lower product cost. Howeve...

Claims

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