Amplifier apparatus

Patent metadata

Field	Value
Publication number	US-9257945-B2
Application number	US-201514690883-A
Country	US
Kind code	B2
Filing date	Apr 20, 2015
Priority date	Jun 25, 2010
Publication date	Feb 9, 2016
Grant date	Feb 9, 2016

Abstract

Disclosed is a technique for reducing noise superimposed on an output signal while keeping loop gain constant without increasing the circuit scale and without changing the transfer function of the amplifier apparatus (frequency characteristics of gain and phase). According to the technique, there are included a power-supply voltage control unit 7 for detecting the amplitude level S 9 of an input audio signal S 1 and outputting power with a voltage value indicated by target set voltage value information Vs corresponding to this amplitude level S 9 , and a PWM modulation unit 2 including a PWM converter 23 for converting the pulse width of the input audio signal S 1 and a correction unit for correcting the signal modulated by the PWM converter 23 . The PWM modulation unit 2 corrects the pulse width of a PWM signal S 5 modulated by the PWM converter 23 so that the correction unit will cancel out a change in amplification gain of a power amplification unit 4 according to the target set voltage value information Vs.

First claim

The invention claimed is:

1. An amplifier apparatus comprising:
a power amplification unit for amplifying a power of an input audio signal by switching a power supply voltage using a pulse width modulation signal appropriate for a level of the input audio signal;
a power-supply voltage control unit for detecting an amplitude level of the input audio signal and applying a target set voltage appropriate for the detected amplitude level of the input audio signal to the power amplification unit as the power supply voltage; and
a PWM modulation unit;
the PWM modulation unit including:
a pulse width conversion unit for converting the input audio signal to a pulse width modulation signal with a pulse width appropriate for the level of the input audio signal; and
a pulse width correction unit for correcting the pulse width of the pulse width modulation signal generated by the pulse width conversion unit based on the target set voltage to cancel out a change in amplification gain of the power amplification unit, and applying the corrected pulse width modulation signal to the power amplification unit.

2. The amplifier apparatus according to claim 1 , characterized in that the pulse width correction unit includes:
a basic clock generating unit for generating a basic clock as a basic timing signal upon conversion of the input audio signal to the pulse width modulation signal;
a ramp slope control unit for generating a ramp wave different in slope according to the target set voltage from the basic clock generated by the basic clock generating unit; and
a correction unit for correcting the pulse width of the pulse width modulation signal generated by the pulse width conversion unit based on the ramp wave generated by the ramp slope control unit.

3. An amplifier apparatus comprising:
a power amplification unit for amplifying a power of an input audio signal by switching a power supply voltage using a pulse width modulation signal appropriate for a level of the input audio signal;
a power-supply voltage control unit for detecting an amplitude level of the input audio signal and applying a target set voltage appropriate for the detected amplitude level of the input audio signal to the power amplification unit as the power supply voltage;
a detection unit for detecting the power supply voltage to be applied to the power amplification unit; and
a PWM modulation unit;
the PWM modulation unit including:
a pulse width conversion unit for converting the input audio signal to a pulse width modulation signal with a pulse width appropriate for the level of the input audio signal;
a basic clock generating unit for generating a basic clock as a basic timing signal upon conversion of the input audio signal to the pulse width modulation signal;
a ramp slope control unit for generating a ramp wave different in slope according to the detected power supply voltage from the basic clock generated by the basic clock generating unit; and
a correction unit for correcting the pulse width of the pulse width modulation signal generated by the pulse width conversion unit based on the ramp wave generated by the ramp slope control unit to cancel out a change in amplification gain of the power amplification unit, and applying the corrected pulse width modulation signal to the power amplification unit.

4. An amplifier apparatus comprising:
a power amplification unit for amplifying a power of an input audio signal by switching a power supply voltage using a pulse width modulation signal appropriate for a level of the input audio signal;
a power-supply voltage control unit for detecting an amplitude level of the input audio signal and applying a target set voltage appropriate for the detected amplitude level of the input audio signal to the power amplification unit as the power supply voltage; and
a PWM modulation unit;
the PWM modulation unit
correcting a level of the input audio signal according to the target set voltage, converting the corrected level of the input audio signal to a corrected pulse width modulation signal, and applying the corrected pulse width modulation signal to the power amplification unit to cancel a change in amplification gain of the power amplification unit.

5. The amplifier apparatus according to claim 4 , characterized in that the PWM modulation unit calculates a difference value between the amplitude level of the input audio signal and a level obtained by attenuating the output of the power amplification unit, and multiplies the calculated difference value by a correction coefficient appropriate for the target set voltage to correct the level of the input audio signal to be subjected to pulse width modulation.

6. The amplifier apparatus according to claim 5 , characterized in that the PWM modulation unit further compares the corrected level of the input audio signal to be subjected to pulse width modulation with a predetermined reference wave to generate the corrected pulse width modulation signal.

7. The amplifier apparatus according to claim 1 , further comprising a feedback unit negatively feeding output of the power amplification unit back to the PWM modulation unit,
wherein the PWM modulation unit corrects the pulse width of the pulse width modulation signal generated by the pulse width conversion unit based on the target set voltage and the output from the feedback unit to cancel out a change in amplification gain of the power amplification unit.

8. The amplifier apparatus according to claim 3 , further comprising a feedback unit negatively feeding output of the power amplification unit back to the PWM modulation unit,
wherein the correction unit corrects the pulse width of the pulse width modulation signal generated by the pulse width conversion unit based on the ramp wave generated by the ramp slope control unit and the output from the feedback unit to cancel out a change in amplification gain of the power amplification unit.

9. The amplifier apparatus according to claim 4 , further comprising a feedback unit negatively feeding output of the power amplification unit back to the PWM modulation unit,
wherein the PWM modulation unit corrects the level of the input audio signal according to the target set voltage and the output from the feedback unit to cancel a change in amplification gain of the power amplification unit.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Zhang Mingxue
• Ozaki Seigo
• Haga Tsuyoshi

Classifications

• H03F2200/351

  Pulse width modulation being used in an amplifying circuit · CPC title

• H03F2200/03

  the amplifier being designed for audio applications · CPC title

• H03F3/217

  Class D power amplifiers; Switching amplifiers · CPC title

• H03F3/183 Primary

  with semiconductor devices only · CPC title

• H03F1/26

  Modifications of amplifiers to reduce influence of noise generated by amplifying elements · CPC title