Analog-to-digital converter employing DC offset cancellation aft

Details Analog-to-digital converter employing DC offset cancellation aft Analog-to-digital converter employing DC offset cancellation aft

1996-01-04

1998-02-24

Gaffin, Jeffrey A.

Coded data generation or conversion

Converter compensation

341119, 341120, 341121, H03M 110

Patent

active

057215472

ABSTRACT:
An analog-to-digital (A/D) converter is provided for converting an analog signal to a digital signal, wherein the digital signal is corrected such that it does not contain DC offset. The A/D converter preferably comprises a delta-sigma modulator and an offset compensation circuit. The offset compensation circuit is coupled to the output of the modulator or, according to another embodiment, to the output of a noise cancellation circuit. The offset compensation circuit can calibrate a single bit output from the modulator or a multi-bit output from the noise cancellation logic. In the former instance, the offset compensation circuit includes an up/down counter and register; in the latter instance, the calibration circuit includes an accumulator. The offset compensation circuit counts or accumulates a digital representation of DC offset. The counted or accumulated value is stored and thereafter subtracted from a digitally represented analog input signal subsequently applied to the modulator during a normal operation mode. Accordingly, the analog input signal is converted to a digital signal absent DC offset.

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