| 摘要 |
A PM/FM modulator ( 100 ) includes an analog-to-digital converter ( 110 ) having an input terminal for receiving an analog input signal, and an output terminal, and a direct digital frequency synthesizer ( 120 ) having an input terminal coupled to the output terminal of the analog-to-digital converter, and an output terminal for providing a modulated output signal. In one form, an FM stereo modulator ( 200 ) includes a digital stereo modulator ( 210 ) and a direct digital frequency synthesizer ( 250 ). The digital stereo modulator ( 210 ) has a first input terminal for receiving a right analog input signal, a second input terminal for receiving a left analog input signal, and an output terminal for providing a digital signal having a stereo spectrum. The direct digital frequency synthesizer ( 250 ) has an input terminal coupled to the output terminal of the digital stereo modulator ( 210 ), and an output terminal for providing a modulated output signal.
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