A CMOS VLSI framer chip for a broadband ISDN local access system

The emerging broadband ISDN will satisfy the present and future needs for a wide range of bit rales and holding times. A broadband ISDN subscriber access prototype
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PI being explored at Bell Communications Research includes highspeed circuit switching, time division multiplexing, packet multiplexing, and packet processing. In order to properly identify data streams in the network, and to allow individual bytes in these streams to be located, a synchronous frame format for a basic channel is adopted as shown in Fig. 1 for use in the prototype. The ultimate bit rate for the basic channel (called WB-1) has not been determined but it is suggested that the bit rate should be in the range of 130–150 Mb/s. The bit rate chosen for the prototype is 139.264 Mb/s.