| 摘要 |
<p>Oversampling DACs suffer tend from idle channel tones when converting low level input signals (192) in spite of the noise-shaping features of the Delta-Sigma modulator (150). In the proposed DAC system a dither signal, which is preferably a square wave, from signal generator (196) is added to the output of the digital filter (120) at the summer (145). The composite multi-bit signal is fed to the delta-sigma modulator (150) for noise-shaping and outputting as a single bit signal from the digital section (110). The single bit signal is input to the analog section (170) including DAC (180) and an analog filter (190). The noise shaping property of the delta-sigma modulation tends to shift any spurious noises to higher frequencies outside the passband of the system where they are readily attenuated through filtering.</p> |
