| 摘要 |
PURPOSE:To enable to obtain wider dynamic range even though the use of low voltage power supply with a simple consitution, by the gain control through the change in the bias voltage of differential pair transistors with the emitter resistor of absorbing current source. CONSTITUTION:To the absorbing current source Q1, DC current including AC component changed in response to the input signal flows, and the transistors TrQ1, Q2 constitute the differential pair in parallel connection with the current source Q3. TrQ4, Q7 in the Miller circuit produce the sum current between the current IQ9 equal to the specified frequency component of the operation current of TrQ2 and the operating current IQ1 of TrQ1. Further, the emitter resistor RE of TrQ3 changes the bias voltage of differential pair TrQ1, Q2 to perform gain control. Accordingly, with a simple constitution, the dynamic renge can be taken greater even through the use of low voltage power supply. |
