D-class amplifier circuit and audio amplifying method

Patent metadata

Field	Value
Publication number	US-11411537-B2
Application number	US-202016950305-A
Country	US
Kind code	B2
Filing date	Nov 17, 2020
Priority date	Nov 18, 2019
Publication date	Aug 9, 2022
Grant date	Aug 9, 2022

Abstract

A circuit includes an input impedance, an operational amplifier, a voltage-adjusting circuit, a pulse-generating circuit, and a drive circuit. The input impedance is coupled to an input terminal of the operational amplifier, receives an input voltage, and outputs an input current. The operational amplifier is coupled to a first power voltage and outputs an amplified signal according to an input operating voltage and a feedback signal. The voltage-adjusting circuit adjusts the input operating voltage of the operational amplifier. The pulse-generating circuit generates a pulse width modulation signal according to the amplified signal. The drive circuit is coupled to a second power voltage and generates a driving signal according to the pulse width modulation signal. The feedback signal is correlated with the driving signal.

First claim

What is claimed is:

1. A circuit, comprising:
an operational amplifier coupled to a first power voltage and configured to output an amplified signal according to an input operating voltage and a feedback signal;
an input impedance coupled to an input terminal of the operational amplifier and configured to receive an input voltage and to output an input current;
a voltage-adjusting circuit configured to adjust the input operating voltage of the operational amplifier;
a pulse-generating circuit configured to generate a pulse width modulation signal according to the amplified signal; and
a drive circuit coupled to a second power voltage and configured to generate a driving signal according to the pulse width modulation signal, the feedback signal being correlated with the driving signal;
wherein the voltage-adjusting circuit supplies an adjusting current to adjust the input operating voltage, and the adjusting current and a difference between the second power voltage and a specific multiple of the first power voltage are in a proportional relationship.

2. A circuit, comprising:
an operational amplifier coupled to a first power voltage and configured to output an amplified signal according to an input operating voltage and a feedback signal;
an input impedance coupled to an input terminal of the operational amplifier and configured to receive an input voltage and to output an input current;
a voltage-adjusting circuit configured to adjust the input operating voltage of the operational amplifier;
a pulse-generating circuit configured to generate a pulse width modulation signal according to the amplified signal; and
a drive circuit coupled to a second power voltage and configured to generate a driving signal according to the pulse width modulation signal, the feedback signal being correlated with the driving signal;
wherein the voltage-adjusting circuit supplies an adjusting current to adjust the input operating voltage, the adjusting current is uncorrelated with the first power voltage, and the adjusting current and a difference between the second power voltage and a specific multiple of a reference voltage are in a proportional relationship.

3. The circuit according to claim 1 , wherein a maximum current value of the second power voltage is greater than or equal to ten times a maximum current value of the first power voltage.

4. A method, comprising:
adjusting an input operating voltage of an operational amplifier powered by a first power voltage;
outputting, by the operational amplifier, an amplified signal according to the input operating voltage and a feedback signal;
outputting a pulse width modulation signal according to the amplified signal; and
generating a driving signal according to the pulse width modulation signal, the driving signal being correlated with the feedback signal;
wherein the step of adjusting the input operating voltage of the operational amplifier comprises supplying an adjusting current to adjust the input operating voltage, and wherein the adjusting current and a difference between a second power voltage and a specific multiple of the first power voltage are in a proportional relationship.

5. The method according to claim 4 , wherein a maximum current value of a second power voltage is greater than or equal to ten times a maximum current value of the first power voltage.

6. The circuit according to claim 2 , wherein a maximum current value of the second power voltage is greater than or equal to ten times a maximum current value of the first power voltage.

Assignees

• Realtek Semiconductor Corp

Inventors

• Lin Che-Hung
• Lai You-Min
• Cheng Kok-Choon
• Kao Li-Lung

Classifications

• H03F2200/03

  the amplifier being designed for audio applications · CPC title

• H03F3/45475

  using IC blocks as the active amplifying circuit · CPC title

• H03F2203/45116

  Feedback coupled to the input of the differential amplifier · CPC title

• H03F3/187

  in integrated circuits · CPC title

• H03F2200/129

  there being a feedback over the complete amplifier · CPC title