| 摘要 |
PURPOSE:To enlarge fairly the dynamic range of an FM signal demodulator by installing a pnp transistor and npn transistor which constitutes an inverted Darlington amplifier together with the pnp transistor to the output section of the multiplier of the demodulator. CONSTITUTION:The output of a multiplier is not connected with an output resistance 41 directly, but its output signal current is taken out through an inverted Darlington amplifier composed of a pnp and npn transistor Q41 and Q42. An npn transistor Q43 and resistance 34 constitute a constant-current source and a fixed base voltage is supplied to the pnp transistor Q41 by means of the constant-current source and a diode Q40 and resistance 39. The collector voltages of transistors Q11 and Q14 which are the output of the multiplier are fixed to the emitter voltage of the pnp transistor Q41 and the signal current is turned back and made to flow to an earth potential side at the inverted Darlington amplifier. The signal current is again turned back and made to flow to the supply voltage side through a transistor 45 constituting a current mirror and outputted to an output terminal 5.
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