| 摘要 |
PURPOSE:To widen the dynamic range of an output even in the use with a low voltage power supply by outputting a collector-emitter voltage through a current mirror circuit. CONSTITUTION:A differential amplifier comprising transistors (TRs) Q1, Q2 is an input amplifier circuit of a power amplifier circuit using a base of the TR Q1 as its input terminal and a base of the TR Q2 as a feedback terminal. The circuit of the current mirror constitution comprising TRs Q3, Q4 is an active load of an input amplifier circuit, resistors R1, R2 decide the DC operating point of the input amplifier circuit and decides the DC operating point of the output stage comprising TRs Q17, Q16 via a resistor R3 being a feedback resistor. Moreover, the resistor R4 decides the AC voltage gain by the ratio of the resistor R3. The TRs Q5, Q8 and Q9 and TRs to extract the output of the input amplifier circuit as the current output and the current output is sent to the output stage by the current mirror.
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