资料介绍
Auto-Zero运放原理Demystifying Auto-Zero Amplifiers―Part 1
They essentially eliminate offset, drift, and 1/f noise. How do they work? Is there a downside?
by Eric Nolan
INTRODUCTION
Auto-Zero Amplifier Principle
Auto-zero amplifiers typically operate in two phases per clock cycle, illustrated in Figures 1a and 1b. The simplified circuit shows a nulling amplifier (AA), a main (wide-band) amplifier (AB), storage capacitors (CM1 and CM2), and switches for the inputs and storage capacitors. The combined amplifier is shown in a typical op-amp gain configuration. In Phase A, the auto-zero phase (Figure 1a), the input signal is applied to the main amplifier (AB) alone; the main amplifier’s nulling input is supplied by the voltage stored on capacitor CM2; and the nulling amplifier (AA) auto-zeros itself, applying
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