A single-chip CMOS analog/digital mixed NTSC decoder

A CMOS LSI that integrates all analog-to-digital (A/D) and digital-to-analog (D/A) circuits, digital signal-processing circuits, and peripherals necessary for a digital NTSC (National Television System Committee) signal decoder on a single chip is described. The chip accepts composite NTSC signals in analog form, digitizes them, converts them to component RGB signals by digital signal processing, and changes the signals to analog form using the on-chip D/As. The key to making the single chip possible is the development of circuits which maximize utilization of the input digital data so that acceptable picture quality can be maintained despite 6-b resolution. Thus a 6-b A/D can be used, resulting in reduced circuit size.<>