Patent ID: 9467774
Filing Date: 2016-10-11
CPC Classification: H03M,H04R

Claim Text:
1. A method comprising: amplifying a signal provided by a microphone to form an amplified signal; converting the amplified signal into a frequency-based signal having a frequency dependent on an amplitude of the amplified signal; and converting the frequency-based signal into a pulse code modulated (PCM) bitstream using a sigma-delta converter, wherein the sigma-delta converter is configured to provide a PCM output code proportional to a frequency of the frequency-based signal, wherein the sigma-delta converter comprises a loop filter having a first input coupled to the frequency-based signal, a second voltage controlled oscillator (VCO) having an input coupled to an output of the loop filter, and a frequency-to-PCM circuit coupled to an output of the second VCO, and wherein an output of the frequency-to-PCM circuit is coupled to a second input of the loop filter.