Patent ID: 9712906
Date: 2017-07-18
CPC Classifications: H03M,H04R

Claim:
1. An apparatus, comprising: a first output node configured to couple to a load; a first digital-to-analog converter (DAC) coupled to the first output node; sense circuitry coupled to the first output node; a reference generator; a second digital-to-analog converter (DAC) coupled to the reference generator; an analog-to-digital converter (ADC) coupled to the sense circuitry and coupled to the reference generator; and digital circuitry coupled to the analog-to-digital converter (ADC) and to the first digital-to-analog converter (DAC) and to the second digital-to-analog converter (DAC) and configured to control the reference generator to determine an impedance of the load, wherein the digital circuitry is configured to perform steps comprising: applying a periodic signal to the load; controlling the reference generator through a control signal to the second digital-to-analog converter (DAC) to generate a reference value; comparing a sensed value received from the sense circuitry with the reference value, wherein the sense circuitry determines a response of the load to the applied periodic signal; and searching for a generated control signal that produces a matching reference value that is within a specified threshold around the sensed value.