Integrated circuit for the color decoder of a television set

摘要

An integrated circuit is provided for the color decoder of a television receiver set and in particular for a multistandard decoder for NTSC, PAL and SECAM. Conventionally employed external components used for synchronizing and amplitude calibration are replaced by circuits forming part of an integrated circuit, which automatically adjust for the desired operational mode such as NTSC, PAL or SECAM in each case. This system saves previously required external components such as trimming resistors, potentiometers or quartz crystals. A digital automatic frequency control circuit can provide the synchronization of oscillators within the integrated circuit which oscillators generate the required reference carriers required for the decoding of the chrominance carrier. In addition, the switches for the processing of signals of various color television standards can be incorporated within the integrated circuit.