| 摘要 |
PURPOSE:To increase a detection gain by providing negative feedback via a diode to a high-gain amplifying circuit which receives a signal to be amplitude-modulated as an input and has a constant-current circuit as a load and by integrating an amplified output. CONSTITUTION:One terminal of a signal source Vs for a signal to be amplitude- modulated is connected to the base of a common emitter transistor (TR) Q1 via a capacitor C2, and the other grounded. The TRQ1 is loaded with a constant-current circuit K composed of a TRQ2, diode D2 and resistance R2. The D3 is connected forward between the collector and base of the TRQ1. A resistance R3 and capacitor C3 constitute an integral network. When a signal Vs is inputted to the circuit with said constitution, the collector current I1 of the TRQ1 increases in the positive half cycle of a carrier and the current I2 of the D3 decreases, increasing the gain of the TRQ1. In the negative half cycle, the current I2 increases and a waveform crushed flat in the positive half cycle is obtained. This is processed by integration F to obtain a high-gain wave detecting output at a terminal (t). |
