| 摘要 |
PROBLEM TO BE SOLVED: To improve the use of the power supply voltage by detecting a drive voltage at a connecting point between 1st and 2nd output transistors (TRs), obtaining a feedback signal proportional to the drive voltage, obtaining an output current signal in response to the difference voltage between an input signal and the feedback signal, converting the current signal into a voltage signal, giving it to the 2nd output TR and controlling the 1st output TR so that a difference between the drive voltage and the output voltage of an amplifier means is made zero. SOLUTION: An input signal Wa is given to a comparison section 21, and a feedback section 25 that detects a drive voltage Va fed from a terminal C being a connecting point of 1st and 2nd output TRs 31, 32 to a load 13, generates a feedback signal H and gives it to the comparison section 21. The comparison section 21 compares the input signal Wa with the feedback signal H and provides the output of a current D in response to the difference voltage. An amplifier section 22 applies current amplification to the current signal D and then converts the amplified signal into voltages E, F, G and outputs them. An operation control section 24 compares the voltage signal F with the drive voltage Va and outputs a signal J in response to the difference voltage of them to a base of the output TR 31 so as to control the TR 31. As a result, the voltage Va is controlled to be in matching with the signal F thereby making the voltage difference between the signal F and the drive voltage Va zero. |
