| 摘要 |
1,172,366. Gain control circuits; transistor amplifiers. RADIO CORPORATION OF AMERICA. 24 Nov., 1966 [29 Nov., 1965], No. 52748/66. Heading H3T. [Also in Division G3] A radio receiver includes a transistor 70 which is associated with a radio frequency tuning circuit 76 and a local oscillator circuit 78 and which produces amplified I.F. signals at the collector thereof; these amplified signals are applied over an I.F. resonant circuit 74 to the base of a further amplifying transistor 84 associated with a second I.F. resonant circuit 86 which is connected to a further amplifier or detector stage (not shown). Bias potentials for transistors 70 and 84 are derived from a separate stabilizing circuit 10 (see Division G3), and automatic gain control is provided by varying these potentials in dependence upon a signal, indicative of input signal variations, which is applied over terminal 96 to the base of transistor 94 connected to the circuit 10. The arrangement is such that variations in the signal at terminal 96 vary the conductivity of transistor 94, whereby the bias potentials from circuit 10 are also varied accordingly. The transistors 70, 84, 94 and the circuit 10 may be an integrated circuit structure. |
