The AK5370 integrates USB serial interface engine, USB transceiver, audio class decoder, endpoints, and high quality AD converter into t he chip. As the AK5370 incorporates PLL, it can support several sampling frequencies, 8kHz, 11.025kHz, 22.05kHz, 44.1kHz, and 48kHz with only one crystal. Moreover, the AK5370 integrates volume control, and mute function. It is possible to make USB microphone with a few external components