Semiconductor power amplification circuit

A power amplification circuit comprising;

• a signal input terminal;
• a drive transistor amplifying the input signals applied to said signal input terminal;
• a bias voltage setting means having one end thereof connected to the collector of said drive transistor;
• a constant current load means connected to the other end of the said bias voltage setting means and operating as a load of said drive transistor;
• a first transistor amplifying the output obtained at said other end of said bias voltage setting means;
• said constant current load means supplying base current to said first transistor;
• a second transistor amplifying the output obtained at said one end of said bias voltage setting means, the collector-emitter paths of said first and second transistors being connected in series between a first and a second power supply line;
• said first supply line supplying current to the collector of said first transistor;
• an output terminal electrically connected to the common connecting terminal of said first and second transistors;
• a third transistor having a base connected to the base of said first transistor said third transistor being of the same conductivity type as said first transistor;
• means for DC-connecting the emitter of said third transistor to that of said first transistor;
• a current mirror circuit having an input circuit connected between the collector of said third transistor and said first power supply line;
• a fourth transistor having a base connected to the output of said current mirror circuit at a first connecting point, an emitter electrically connected to said output terminal, and a collector connected to said constant current load means;
• and a current-voltage conversion means connected between said first connecting point and said second power supply line.