| 摘要 |
A CIRCUIT TOPOLOGY AND METHOD FOR CONVERTING A DIGITAL INPUT SIGNAL TO AN ANALOG OUTPUT SIGNAL EMPLOYS A MODIFIED SIGMA-DELTA LOOP AND A DAC, AND OPERATES WITH IMPROVED ACCURACY OVER A WIDE FREQUENCY RANGE. A LOOP FILTER SUCH AS A DIGITAL ACCUMULATOR RECEIVES AN INPUT SIGNAL PROPORTIONAL TO THE DIFFERENCE BETWEEN A DIGITAL INPUT SIGNAL AND A FEEDBACK SIGNAL. A QUANTIZER QUANTIZES THE OUTPUT OF THE LOOP FILTER, AND THE DAC CONVERTS THE QUANTIZED SIGNAL INTO AN ANALOG OUTPUT SIGNAL. THE QUANTIZED SIGNAL IS ALSO PROVIDED TO A DAC MODEL. IN RESPONSE TO THE QUANTIZED SIGNAL AND BEHAVIORAL INFORMATION ABOUT THE DAC, THE DAC MODEL VARIES THE FEEDBACK SIGNAL TO MATCH EXPECTED OUTPUT SIGNALS FROM THE DAC, INCLUDING ERRORS INTRODUCED BY THE DAC. BY THE OPERATION OF THE SIGMA-DELTA LOOP, THE ERRORS OF THE DAC ARE SUBSTANTIALLY REDUCED.
|
