Switching power amplifier, and switching control method for a switching power amplifier

• US 6,831,508 B2
• Filed: 05/08/2003
• Issued: 12/14/2004
• Est. Priority Date: 02/19/2001
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Shima, Takashi
• Primary Examiner(s): Mottola, Steven J.
• Application Number:
  US10/257,421
• Publication Number:
  US 20030169103A1
• Time in Patent Office: 586 Days
• Field of Search: 330/10, 330/207.A, 330/251, 330/297
• US Class Current: 330/10
• CPC Class Codes: H03F 1/3205 in field-effect transistor amplifiers
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H03F 3/2173 of the bridge type

Abstract

A reduction is made in signal distortion that occurs in an output signal of a PWM switching power amplifier due to noise disturbances from a switching power supply. In a switching power amplifier that has a switching power supply unit, a clock signal for controlling the switching of the switching power supply unit is generated based on a clock signal that is used to synchronize switching operations. The clock signal has a clock period that is an integer multiple of a period t of the clock signal and matches a timing at which a signal level of a PWM power signal that is generated by the switching power amplifier is at ground level. The switching of the switching power supply unit is synchronized using the clock signal.

Claims

1. A switching power amplifier, comprising:

pulse width modulation converting means for performing a conversion of an input signal into a pulse width modulation signal;

pulse width modulation clock signal generating means for generating a first clock signal that has a reference period for conversion of the input signal into the pulse width modulation signal and supplying the first clock signal to the pulse width modulation converting means, so that a timing of a fixed edge of the pulse width modulation signal is based on the first clock signal;

power switching means controlled by the pulse width modulation signal;

a switching power supply unit for supplying power to the power switching means; and

power supply clock signal generating means for generating a second clock signal based on the first clock signal that has a reference period for switching operations of the switching power supply unit and supplying the second clock signal to the switching power supply unit,

wherein a starting edge of the second clock signal that is generated by the power supply clock signal generating means is formed during a period between the fixed edge of the pulse width modulation signal and a moveable edge that follows the fixed edge.

2. The switching power amplifier according to claim 1, wherein

the second clock signal generated by the power supply clock signal generating means is generated in synchronization with the first clock signal generated by the pulse width modulation clock signal generating means.

3. The switching power amplifier according to claim 2, wherein the power supply clock signal generating means forms a starting edge of the second clock signal a predetermined time after detecting a starting edge in the first clock signal generated by the pulse width modulation clock signal generating means.

4. The switching power amplifier according to claim 1, wherein

the first clock signal generated by the pulse width modulation clock signal generating means is generated in synchronization with the second clock signal generated by the power supply clock signal generating means.

5. The switching power amplifier according to claim 4, wherein

the pulse width modulation clock signal generating means forms a starting edge of the first clock signal a predetermined time after detecting a starting edge in the second clock signal generated by the power supply clock signal generating means.

6. The switching power amplifier according to claim 1, wherein

the starting edge of the second clock signal generated by the power supply clock signal generating means is formed between a movable edge of the pulse width modulation signal for a case of maximum modulation of the pulse width modulation signal and a fixed edge that follows the movable edge.

7. The switching power amplifier according to claim 1, wherein

the power supply clock signal generating means forms a starting edge of the second clock signal a predetermined time after detecting a movable edge of the pulse width modulation signal.

8. The switching power amplifier according to claim 1, wherein

a period of the second clock signal generated by the power supply clock signal generating means is n times a period of the first clock signal generated by the pulse width modulation clock signal generating means, n being an integer that is 1 or greater.

9. The switching power amplifier according to claim 1,

further comprising master clock signal generating means for generating a master clock signal supplied to pulse width modulation clock signal generating means and to the power supply clock signal generating means as a reference clock signal, the master clock signal having a period that is 1/m in of a period of the first clock signal, in being an integer that is 1 or greater.

10. A switching control method for a switching power amplifier that includes a pulse width modulation converting unit receiving an input signal and a switching power supply unit,

comprising a step of controlling a second clock signal that is based on a clock signal of the pulse width modulation converting unit, which has a reference period for switching operations of the switching power supply unit, so that a starting edge of the second clock signal is formed between a fixed edge of a pulse width modulation signal formed from the input signal and a moveable edge that follows the fixed edge.

11. A switching control method for a switching power amplifier that includes a pulse width modulation converting unit receiving an input signal and a switching power supply unit,

comprising a step of controlling the switching power supply unit so that a starting edge of a second clock signal that is based on a first clock signal of the pulse width modulation converting unit, which has a reference period for switching operations of the switching power supply unit, is formed between a fixed edge of a pulse width modulation signal formed from the input signal for a case of maximum modulation of the pulse width modulation signal and a moveable edge that follows the fixed edge.

12. A switching power amplifier, comprising:

pulse width modulation converting means for performing a conversion of an input signal into a first pulse width modulation signal and a second pulse width modulation signal, the first pulse width modulation signal and the second pulse width modulation signal being a two'"'"'s complement of each other;

pulse width modulation clock signal generating means for generating a first clock signal that has a reference period fed to the pulse width modulation converting means for controlling a timing of converting the input signal into the first pulse width modulation signal and the second pulse width modulation signal and supplying the first clock signal to the pulse width modulation converting means;

first power switching means controlled by the first pulse width modulation signal;

second power switching means controlled by the first pulse width modulation signal;

a switching power supply unit for supplying power to the first power switching means and the second power switching means; and

power supply clock signal generating means for generating a second clock signal based on the first clock signal that has a reference period for switching operations of the switching power supply unit and supplying the second clock signal to the switching power supply unit, wherein

a starting edge of the second clock signal that is generated by the power supply clock signal generating means and that is based on the first clock signal is formed during a period where the first pulse width modulation signal and the second pulse width modulation signal have an equal potential level.

13. The switching power amplifier according to claim 12, wherein

a starting edge of the second clock signal generated by the power supply clock signal generating means is formed during one of:

a first period between a fixed edge of the first pulse width modulation signal and a moveable edge that follows the fixed edge; and

a second period between a movable edge of the first pulse width modulation signal and a fixed edge that precedes the movable edge.

14. The switching power amplifier according to claim 12, wherein

the second clock signal generated by the power supply clock signal generating means is generated in synchronization with the first clock signal generated by the pulse width modulation clock signal generating means.

15. The switching power amplifier according to claim 14, wherein

the power supply clock signal generating means forms a starting edge of the second clock signal a predetermined time after detecting a starting edge in the first clock signal generated by the pulse width modulation clock signal generating means.

16. The switching power amplifier according to claim 12, wherein

the first clock signal generated by the pulse width modulation clock signal generating means is generated in synchronization with the second clock signal generated by the power supply clock signal generating means.

17. The switching power amplifier according to claim 16, wherein

the pulse width modulation clock signal generating means forms a starting edge of the first clock signal a predetermined time after detecting a starting edge in the second clock signal generated by the power supply clock signal generating means.

18. The switching power amplifier according to claim 12, wherein

a starting edge of the second clock signal generated by the power supply clock signal generating means is formed during one of:

a first period between a fixed edge of the first pulse width modulation signal for a case of maximum modulation of the first pulse width modulation signal and a moveable edge that follows the fixed edge; and

a second period between a movable edge of the first pulse width modulation signal for a case of minimum modulation of the first pulse width modulation signal and a fixed edge that precedes the movable edge.

19. The switching power amplifier according to claim 12, wherein the power supply clock generating means forms a starting edge of the second clock signal a predetermined time after detecting a movable edge in the first pulse width modulation signal.

20. The switching power amplifier according to claim 12, wherein

a period of the second clock signal generated by the power supply clock signal generating means is n times a period of the first clock signal generated by the pulse width modulation clock signal generating means, n being an integer that is 1 or greater.

21. The switching power amplifier according to claim 12,

further comprising master clock signal generating means for generating a master clock signal supplied to the pulse width modulation clock signal generating means and to the power supply clock signal generating means as a reference clock signal, the master clock signal having a period that is 1/m of a period of the first clock signal, m being an integer that is 1 or greater.

22. A switching control method for a switching power amplifier that includes a pulse width modulation converting unit receiving an input signal a switching power supply unit,

comprising a step of controlling a second clock signal, which has a reference period for switching operations of the switching power supply unit and which is based on a first clock signal of the pulse width modulation converting unit, so that a starting edge of the second clock signal is formed during one of:

a first period between a moveable edge of a first pulse width modulation signal that is formed from the input signal and a fixed edge that precedes the movable edge; and

a second period between a movable edge of a second pulse width modulation signal that is a two'"'"'s complement of the first pulse width modulation signal and a fixed edge that precedes the movable edge.

23. A switching control method for a switching power amplifier that includes a pulse width modulation converting unit receiving an input signal and a switching power supply unit,

comprising a step of controlling a second clock signal, which has a reference period for switching operations of the switching power supply unit and which is based on a first clock signal of the pulse width modulation converting unit, so that a starting edge of the second clock signal is formed during one of:

a first period between a movable edge of a first pulse width modulation signal that is formed from the input signal for a case of maximum modulation of the first pulse width modulation signal and a fixed edge that precedes the movable edge; and

a second period between a movable edge of a second pulse width modulation signal that is a two'"'"'s complement of the first pulse width modulation signal for a case of maximum modulation of the second pulse width modulation signal and that precedes the movable edge.