| 摘要 |
<p>An autozero loop for eliminating offsets in an analog to digital converter section for a voice frequency codec-decoder (CODEC) (10) utilizing an array of capacitors (44) and a linear resistor string (64). The autozero loop functions with a relatively small time constant to null offsets quickly during the power-up phase of CODEC operation and with a higher time constant after the power-up phase. A dual bandwidth sub-circuit (90) in the loop is connected to a voltage generator (88) and controlled by signals from a logic circuit (72) to operate at different bandwidths and thus provide different offset cancelling feedback signals during the power-up and normal operating phases. </p> |
