| 摘要 |
A receiver comprising a sigma-delta analog-to-digital converter ( SIGMA DELTA ADC) can be utilized in one of four configurations, as a subsampling bandpass receiver, a subsampling baseband receiver, a Nyquist sampling bandpass receiver, or a Nyquist sampling baseband receiver. For subsampling SIGMA DELTA receivers, the sampling frequency is less than twice the center frequency of the input signal into the SIGMA DELTA ADC. For Nyquist sampling SIGMA DELTA receivers, the sampling frequency is at least twice the highest frequency of the input signal into the SIGMA DELTA ADC. For baseband SIGMA DELTA receivers, the center frequency of the output signal from the SIGMA DELTA ADC is approximately zero or DC. For bandpass SIGMA DELTA receivers, the center frequency of the output signal from the SIGMA DELTA ADC is greater than zero. The sampling frequency can be selected based on the bandwidth of the input signal to simplify the design of the digital circuits used to process the output samples from the SIGMA DELTA ADC. Furthermore, the center frequency of the input signal can be selected based on the sampling frequency and the bandwidth of the input signal. The SIGMA DELTA ADC within the receiver provides many benefits.
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