| 摘要 |
Sigma delta modulators and pipelined (also called subranging) converters are used widely in Analog to Digital converters. In general pipelined converters are preferred where the highest speed of conversion is required and sigma delta converters are preferred for lower speed where a significant level of oversampling is possible. The present application describes a converter having the advantages of both types of converter. In particular, it discloses an analog to digital converter for converting an analog input signal (21) to a digital output signal (30), comprising a first converter having a filter means (25) for producing at least one filter output signal (31) by filtering the difference between the analog input signal and a feedback signal (32) generated from a first digital output, a quantizer (22) for producing the first digital output (28) by quantizing the weighted sum of a first filter output from the filter means and the analog input signal, a second converter for producing a second digital output by converting a second filter output (31) from the filter means (25), and a digital combiner (29) for combining the first output digital signal and the second output digital signal into the digital output signal.
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