| 摘要 |
PURPOSE:To improve a spurious characteristic at the time of a large input by offsetting nonlinear operation manually when starting operating, by adapting an NPN and a PNP transistors(TR) to a TR for automatic gain control which controls the input level of an antenna. CONSTITUTION:The AGC TR7 uses the NPNTR7a and PNPTR7b, and the series circuit of a capacitor 8, the collector and emitter of the TR7a, and the emitter and collector of the TR7b is connected between the input stage of a high frequency amplification stage 2 and the ground; and an AGC signal is applied to the base of the TR7b, and the base of the TR7a is grounded. The emitter current of the TR7 when it starts operating flows so that nonlinear parts of VBE- IE characteristics of the TRs 7a and 7b cancel each other, so higher-harmonic distortion is reduced considerably to improve the spurious characteristic. |
