| 摘要 |
A method and system for quantizing an analog input signal. The method includes the step of concurrently feeding an input signal and a test signal to the sigma-delta modulator. The modulator provides a common filter for a composite signal comprising the test signal and quantization noise generated in the modulator. The modulator thus produces an output signal comprising a quantized input signal and the commonly filtered composite signal. The modulator output signal is fed to an adaptive quantization noise canceler. The adaptive quantization noise canceler combines the modulator output signal with a quantization noise nulling signal to produce a quantization noise compensated output signal. The quantization noise nulling signal is produced by detecting the test signal component in the quantization noise compensated output signal and modifying the composite signal, also fed to the adaptive quantization noise canceler, in accordance with detected test signal in a feedback loop which nulls the test signal component in the quantization noise compensated output signal. With such an arrangement, because the quantization noise component has been commonly filtered with the test signal, modifying the composite signal in accordance with detected test signal to null the test signal component in the quantization noise compensated output signal also cancels the quantization noise component in the quantization noise compensated output signal.
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