| 摘要 |
1,183,384. Transistor gain control circuits. ASSOCIATED SEMI-CONDUCTOR MFRS. Ltd. 31 March, 1967, No. 14774/67. Heading H3T. [Also in Division H1] An automatic gain control circuit includes a semi-conductor device comprising a transistor having emitter, base and collector regions and a low resistivity region which forms a PN junction with the collector region. A current path may be provided in the device between the base region and the low resistivity region (see Division H1). If the collector/base and collector/ low resistivity region junctions are both reversed-biased, the collector body resistance may be varied, thus providing gain control, by variation of the degree of biasing since this will vary the width of the two depletion regions within the collector. In the a.g.c. circuit shown A is a tuned circuit, B is a further amplification stage, C is a detector stage and D is an a.g.c. signal amplifier. The amplified a.g.c. signal is applied simultaneously to the base region and to the low resistivity region contiguous with the collector. In an alternative circuit, Fig. 12 (not shown), the a.g.c. signal is applied only to a fourth terminal attached to the low resistivity region. |
