Direct coupling type power amplifier circuit

A direct coupling type power amplifier circuit comprising:

• an input differential amplifier stage having first and second input electrodes, an input signal being supplied to said first input electrode;
• a drive amplifier stage responsive to the output signal of said input differential amplifier stage dc-wise and ac-wise;
• a push-pull output amplifier stage responsive to the output signal of said drive amplifier stage dc-wise and ac-wise;
• a negative feedback circuit network coupled between said push-pull output amplifier stage and said second input electrode of said input differential amplifier stage, the output of said push-pull output amplifier stage being supplied to said second input electrode of said input differential amplifier stage through said negative feedback circuit network;
• a bias circuit network coupled with said input differential amplifier stage for defining the dc bias current through said input differential amplifier stage, said bias circuit network including constant voltage means for providing a constant voltage;
• and
• a delay circuit means coupled between said bias circuit network and a first power source voltage supply point to which a first power source voltage is supplied, said delay circuit means providing a predetermined delay time,
• whereby the dc bias current through said input differential amplifier stage is cut off to hold the whole power amplifier circuit non-responsive to said input signal supplied to said first input electrode of said input differential amplifier stage during a predetermined time interval after the application of said first power source voltage to said first power source voltage supply point, said predetemined time interval being substantially determined by the delay time of said delay circuit means and the constant voltage of said constant voltage means in said bias circuit network.