| 摘要 |
A two-stage bandpass sigma-delta converter (402) suitable for use with signals having multiple protocols is taught. In a first stage (402-1), an alias input signal (X) is applied to two filters (412, 415) having desired and preferably programmable filter characteristics. The sum of the filtered input signal plus a quantization noise of the first stage is applied to a third filter (410) having a programmable center frequency. This provides a first intermediate output signal (Y1) of desired selectivity. The quantization noise of the first stage is also applied to a second stage (402-2) which provides a second intermediate output signal (Y2) having a first component related to the quantization noise of the first stage and a second component which is the shaped quantization noise of the second stage. The first and second intermediate output signals are combined in order to provide a desired output signal (Y). |
