| 摘要 |
PURPOSE: A time division digital filter and a multi channel DA(Digital Analog) conversion circuit are provided to convert a digital audio signal into an analog audio signal by using a time division digital filter which shares plural multipliers and adders and filters digital signals of multi channels. CONSTITUTION: The circuit comprises a digital audio interface(40), a mute module(50), a deemphasis/low pass filter(60), an interpolator(70), a digital sigma-delta converter(80), and a switch capacitor filter(90). The digital audio interface(40) distributes input digital audio to a corresponding channel. The mute module(50) weakens input signals if necessary. The deemphasis/low pass filter(60) attenuates noise components of a high frequency band of the input digital audio signal, performs a low pass filtering operation, and generates a digital signal whose bandwidth is limited. The interpolator(70) increases a sampling speed while a bandwidth of a signal is being conserved. The digital sigma-delta converter(80) feeds an output signal back to an input signal, and transits a white noise to a high frequency band. The switch capacitor filter(90) eliminates the white noise and converts the demodulated digital signal into the analog signal.
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