Patent ID: 8150349

Claim:
An apparatus for audio conversion to generate an audio transmission signal with a predetermined frequency in an FM frequency band comprising: a digital FM (frequency modulation) modulator for modulating a digital audio input signal into a first digital audio signal; a digital frequency synthesizer for frequency-synthesizing the first digital audio signal in a fine-tuning manner into a second digital audio signal; a signal converter, coupled to the digital frequency synthesizer, for converting the second digital audio signal into an analog audio signal; an analog frequency converter, coupled to the signal converter, for generating the audio transmission signal with the predetermined frequency in a coarse-tuning manner according to a second clock signal and the analog audio signal while the second clock signal is generated according to a first clock signal; and a lookup table, for storing a first frequency conversion parameter and a second frequency conversion parameter, wherein a frequency of the second digital audio signal is determined according to a first frequency conversion parameter, and a frequency of the second clock signal is determined according to a frequency of the first clock signal and a second frequency conversion parameter, so that the predetermined frequency is determined according to the frequency of the second clock signal and a frequency of the analog audio signal.