| 摘要 |
PURPOSE:To obtain a variable gain circuit that is suitable for integration and the most adequate for a tape deck, etc., by closely setting the variable width of a gain through the emitter resistances of two transistors applied with an input signal in common at their bases. CONSTITUTION:An input signal is applied in common to bases of transistor TRs Q5 and Q6 to extract an output signal as the sum of an amplified component and attenuated component, and the variable range can freely be set by emitter resistances R2 and R3 of TRs Q5 and Q6. Consequently, the variable width of the gain is closely selected, so that the variable gain circuit can be formed which is nearly equal in circuit scale to the conventional circuit and adequate for integration. |
