| 摘要 |
PCT No. PCT/SE80/00047 Sec. 371 Date Nov. 9, 1980 Sec. 102(e) Date Sep. 29, 1980 PCT Filed Feb. 20, 1980 PCT Pub. No. WO80/01975 PCT Pub. Date Sep. 18, 1980.A gain control circuit includes at least a first (T1, T2) and a second (T3, T4) transistor differential amplifier the input circuits of which are connected in parallel to a signal voltage source. The gain control is performed by distributing a constant current (Is) between these differential amplifiers as a function of a control quantity (Uc) for setting the transconductance of the stages in a complementary way. The two differential amplifiers are provided with negative feed back (F, R1, R2, R3) but with different feed back factors. As the transistors in the differential amplifiers carrying signals of the same phase are interconnected the output signal from the automatic gain control circuit will consist of a superposition of the output signals of the two differential amplifiers. |
