| 摘要 |
PURPOSE:To obtain high resistance to the noise by providing the cascode amplifier step to the front stage of the driving step which drives the power amplifying part plus the decoupling circuit to the negative pole side of the power source. CONSTITUTION:Transistors 16 and 18 form the cascode amplifier step; and transistors 27 and 28 form the equivalent PNP transistor to then constitute the SEEP output step along with Darlington-connected transistors 34 and 35. At the same time, transistors 31 and 32 function as the constant current load of transistor 25; and diodes 29 and 30 function as the bias circuit which decides the idle current of the SEEP output step. Furthermore, Zener diode 20, resistances 22 and 24 plus capacitor 23 form a decoupling circuit. And capacitor 37 functions not only as the output-coupled capacitor but as the bootstrap capacitor for transistors 31, 32 and 34 each. |
