| 摘要 |
<p>1312422 Detector circuits MOTOROLA Inc 19 April 1971 [13 April 1970] 23932/71 Heading H3T An integrated circuit A.M. detector, e.g. in a colour TV receiver, comprises: a mixer 40, 50, 61, 62 with the modulated input (from I.F. amplifier 11) applied to one input; a limiter 70 to which the modulated signal is also applied; a tuned circuit 84, 85 resonant at the carrier frequency coupled to the output of the limiter; and means coupling the output of the limiter to the other input of the mixer. The mixer is formed as a double balanced circuit. The resonant circuit is parallel tuned to the video carrier frequency and includes a further capacitor to give series resonance at the chroma sub-carrier. The limiter 70 comprises long-tailed pair 71, 72 with hot carrier diodes connected between the collectors.</p> |
