Power efficiency improvement of an audio amplifier by adaptive control of a charge pump

Patent metadata

Field	Value
Publication number	US-9329613-B2
Application number	US-201313733595-A
Country	US
Kind code	B2
Filing date	Jan 3, 2013
Priority date	Jan 6, 2012
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A control circuit and method for an audio amplifier detect a signal for driving a speaker to control the switching frequency and the operation mode of a charge pump in the audio amplifier, to improve power efficiency of the audio amplifier. Preferably, a digital interface is further used to test the magnitude of the output signal of the audio amplifier, to reduce the costs of analog test. The charge pump has fewer switches and thus saves costs and die area of an integrated circuit. The control method needs only two phase control for the charge pump to generate a positive voltage and a negative voltage, and thus simplifies the operation of the circuit.

First claim

What is claimed is:

1. A charge pump comprising:
a first bonding pad and a second bonding pad for a first flying capacitor connected therebetween;
a third bonding pad and the second bonding pad for a second flying capacitor connected therebetween;
an input terminal configured to operably receive an input voltage;
a first output terminal connected to a first output capacitor, configured to operably provide a positive voltage;
a second output terminal connected to a second output capacitor, configured to operably provide a negative voltage;
a first switch connected between the input terminal and the first bonding pad;
a second switch connected between the second bonding pad and a ground terminal;
a third switch connected between the third bonding pad and the ground terminal;
a fourth switch connected between the first bonding pad and the first output terminal;
a fifth switch connected between the second bonding pad and the first output terminal;
a sixth switch connected between the third bonding pad and the second output terminal;
a clock generator connected to the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch, configured to operably generate first signal, second signal, third signal, fourth signal, fifth signal and sixth signal to control the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch, respectively;
a detector connected to the first bonding pad, configured to operably detect a first voltage of the first bonding pad to generate a second voltage related to the first voltage;
a reference voltage generator configured to operably provide a variable reference voltage for controlling the positive voltage or the negative voltage; and
a comparator connected to the detector and the reference voltage generator, configured to operably compare the second voltage with the reference voltage to turn off the first switch when the second voltage becomes greater than the reference voltage.

2. The charge pump of claim 1 , wherein during a first operation state of a first mode of the charge pump, the first, third, fourth and fifth switches are turned on and the second and sixth switches are turned off; during a second operation state of the first mode of the charge pump, the first, third, fourth and fifth switches are turned off and the second and sixth switches are turned on; during a first operation state of a second mode of the charge pump, the first, third and fifth switches are turned on and the second, fourth and sixth switches are turn off; during a second operation state of the second mode of the charge pump, the first, third and fifth switches are turned off and the second, fourth and sixth switches are turned on.

3. The charge pump of claim 1 , further comprising a seventh switch connected between the first bonding pad and the ground terminal, controlled by a seventh signal provided by the clock generator.

4. The charge pump of claim 3 , wherein during a first operation state of a first mode of the charge pump, the first, third and fourth switches are turned on and the second, fifth, sixth and seventh switches are turned off; during a second operation state of the first mode of the charge pump, the first, second, third, fourth and fifth switches are turned off and the sixth and seventh switches are turned on; during a first operation state of a second mode of the charge pump, the first, third and fifth switches are turned on and the second, fourth, sixth and seventh switches are turned off; and during a second operation state of the second mode of the charge pump, the first, third, fifth and seventh switches are turned off and the second, fourth and sixth switches are turn on.

5. A charge pump comprising:
a first bonding pad and a second bonding pad for a first flying capacitor connected therebetween;
a third bonding pad and the second bonding pad for a second flying capacitor connected therebetween;
an input terminal configured to operably receive an input voltage;
a first output terminal connected to a first output capacitor, configured to operably provide a positive voltage;
a second output terminal connected to a second output capacitor, configured to operably provide a negative voltage;
a first switch connected between the input terminal and the first bonding pad;
a second switch connected between the second bonding pad and a ground terminal;
a third switch connected between the third bonding pad and the ground terminal;
a fourth switch connected between the first bonding pad and the first output terminal;
a fifth switch connected between the second bonding pad and the first output terminal;
a sixth switch connected between the third bonding pad and the second output terminal; and
a clock generator connected to the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch, configured to operably generate first signal, second signal, third signal, fourth signal, fifth signal and sixth signal to control the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch, respectively;
wherein during a first operation state of a first mode of the charge pump, the first, third, fourth and fifth switches are turned on and the second and sixth switches are turned off; during a second operation state of the first mode of the charge pump, the first, third, fourth and fifth switches are turned off and the second and sixth switches are turned on; during a first operation state of a second mode of the charge pump, the first, third and fifth switches are turned on and the second, fourth and sixth switches are turn off; during a second operation state of the second mode of the charge pump, the first, third and fifth switches are turned off and the second, fourth and sixth switches are turned on.

6. A charge pump comprising:
a first bonding pad and a second bonding pad for a first flying capacitor connected therebetween;
a third bonding pad and the second bonding pad for a second flying capacitor connected therebetween;
an input terminal configured to operably receive an input voltage;
a first output terminal connected to a first output capacitor, configured to operably provide a positive voltage;
a second output terminal connected to a second output capacitor, configured to operably provide a negative voltage;
a first switch connected between the input terminal and the first bonding pad;
a second switch connected between the second bonding pad and a ground terminal;
a third switch connected between the third bonding pad and the ground terminal;
a fourth switch connected between the first bonding pad and the first output terminal;
a fifth switch connected between the second bonding pad and the first output terminal;
a sixth switch connected between the third bonding pad and the second output terminal;
a clock generator connected to the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch, configured to operably generate first signal, second signal, third signal, fourth signal, fifth signal and sixth signal to control the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch, respectively; and
a seventh switch connected between the first bonding pad and the ground terminal, controlled by a seventh signal provided by the clock generator;
wherein during a first operation state of a first mode of the charge pump, the first, third and fourth switches are turned on and the second, fifth, sixth and seventh switches are turned off; during a second operation state of the first mode of the charge pump, the first, second, third, fourth and fifth switches are

Assignees

• Richtek Technology Corp
• Richtek Technology Corp

Inventors

• Ting Chia-Din

Classifications

• G05F3/02 Primary

  Regulating voltage or current · CPC title

• H03G1/0094

  using switched capacitors · CPC title

• H03G3/20

  Automatic control ({H03G3/005 takes precedence;} combined with volume compression or expansion H03G7/00) · CPC title