Closed-loop digital compensation scheme
AssigneeCirrus Logic, Inc.
InventorsLei Zhu, Xin Zhao, John L. Melanson
Life of this patent
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Abstract
Resistor mismatch may be digitally compensated based on a known resistor mismatch, power supply information, and/or other operating parameters of the amplifier. The digital compensation may be applied to the digital input signal before conversion for processing and amplification in the analog domain. An amplifier with digital compensation for resistor mismatch may be used in a class-D amplifier with a closed loop and feedforward feedback. A class-D or other amplifier with digital compensation may be integrated with electronic devices such as mobile phones.
Claims24
A method for amplifying an audio signal with audio amplifier circuitry, comprising:
- receiving a digital input signal representing the audio signal;
- applying a digital compensation to the digital input signal to compensate for resistor mismatch in resistors of the audio amplifier circuitry to generate a compensated digital input signal, wherein the digital compensation is based, at least in part, on a resistor mismatch and a supply voltage;
- converting the compensated digital input signal to an analog signal;
- and
- amplifying the analog signal to produce an amplified analog signal for reproducing the audio signal.
An audio amplifier circuit, comprising:
- a digital compensation block coupled to a digital input node and configured to apply digital compensation to compensate for resistor mismatch to a digital input signal to generate a compensated digital input signal, wherein the digital compensation is based, at least in part, on a resistor mismatch and a supply voltage;
- a digital-to-analog converter (DAC) configured to receive the compensated digital input signal and configured to convert the compensated digital input signal to an input analog signal;
- and
- an amplifier configured to output to amplify the input analog signal to produce an amplified analog signal.
A method for measuring resistor mismatch in an amplifier, the method comprising:
- powering down a power stage of the amplifier, wherein the power stage is coupled to an analog output node;
- driving a load attached to the analog output node from a non-power stage of the amplifier coupled to the analog output node through the power stage, wherein the load is driven to a voltage different from a common mode voltage of a digital-to-analog converter (DAC) of the amplifier;
- monitoring a differential input to the non-power stage;
- and
- adjusting a digital compensation applied to a digital input node based, at least in part, on the differential input, wherein the adjusted digital compensation produces a compensated digital input signal, and wherein driving the load is based on the compensated digital input signal.
An apparatus, comprising:
- a digital compensation block coupled to a digital input node and configured to apply a code to compensate for resistor mismatch in resistors between a digital-to-analog converter (DAC) and an amplifier, wherein applying the code produces a compensated digital input signal;
- a digital-to-analog converter (DAC) coupled to an analog input node and configured to convert the compensated digital input signal to an input analog signal at the analog input node;
- an amplifier comprising an analog output node, wherein the amplifier is configured to output to the analog output node an amplified version of the input analog signal received from the analog input node;
- and
- a controller coupled to the amplifier and to the digital compensation block, wherein the controller is configured to perform steps comprising:
- powering down a power stage of the amplifier, wherein the power stage is coupled to the analog output node;
- driving a load attached to the analog output node from a non-power stage component of the amplifier coupled to the analog output node through the power stage, wherein the load is driven to a reference voltage different from a common mode voltage of a digital-to-analog converter (DAC) coupled to the power stage of the amplifier;
- monitoring a differential input to the non-power stage component;
- and
- adjusting a digital compensation applied to a digital input node using the digital compensation block, wherein the digital compensation is based, at least in part, on the differential input.
Dependencies are inferred from the claim text.