TELEVISION RECEIVER CIRCUITRY

摘要

1285493 Transistor amplifying and detecting circuits; automatic gains control RCA CORPORATION 2 March 1970 [3 March 1969] 9877/70 Heading H3T [Also in Division H1] In a television receiver an I.F. amplifier and a video detector are combined in one integrated circuit chip. An embodiment comprises a single chip which includes a preliminary I.F. amplifier 31, Fig. 4, a final video I.F. amplifier 32, video detector 33 and amplifier 34, an auxiliary I.F. amplifier 35 for sound, an intercarrier sound detector 36 and I.F. amplifier 37, and an A.G.C. circuit 38. The Specification discloses a chip construction (Fig. 6, not shown, see Division H1), and also detailed descriptions of the preliminary I.F. amplifier (Fig. 7, not shown) which forms the subject-matter of copending Application No. 9874/70, of the final I.F. amplifier circuit (Fig. 8, not shown) which forms the subjectmatter of copending Application No. 9875/70 and of the video detector (transistors Q303- Q309, Fig. 8) which forms the subject-matter of Specification 1,259,933. The auxiliary I.F. amplifier 35 comprises transistors Q311, Q313, Fig. 9, followed by transistor Q315, which forms the interearrier sound detector 36. Detector transistor Q315 feeds into transistor Q317 of emitter-coupled pair Q317, Q319 which with transistors Q321, Q323 forms the intercarrier sound I.F. amplifier 37. D.C. feedback over resistors R325, R326 into transistor Q319 stabilizes the arrangement.