×

Power amplifier circuit for audio signal and audio device using the same

  • US 5,450,036 A
  • Filed: 02/22/1994
  • Issued: 09/12/1995
  • Est. Priority Date: 02/23/1993
  • Status: Expired due to Term
First Claim
Patent Images

1. A device for amplifying an audio signal and supplying the amplified signal to a load, comprising:

  • a first amplifier circuit for amplifying the audio signal;

    an output stage amplifier for amplifying an output of said first amplifier circuit and outputting it to said load;

    a switching circuit including a ramp wave generator circuit oscillating at a frequency in a range from 50 kHz to 800 kHz, a comparator having one input supplied with an output of said ramp wave generator circuit and another input supplied with a control signal and a switching transistor for ON/OFF switching of power supplied from a power source line in accordance with an output of said comparator for feeding power to said output stage amplifier;

    a smoothing circuit having a coil provided between the feed power output of said switching circuit and a terminal of said output stage amplifier for receiving the feed power and having a diode for forming a circulating path for supplying said output stage amplifier with a current of said coil in a period when said switching transistor is in an OFF state;

    a control circuit including a control voltage value generator circuit for generating a voltage value corresponding to a voltage difference between a voltage signal of the feed power and a voltage of an output signal of said output stage amplifier as the control signal, and supplying the voltage value to said another input of said comparator to control the comparator output for controlling a switching period of said switching transistor such that the voltage difference between the voltage of said output signal and the voltage of the feed power becomes substantially constant.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×