S3029

The function of the S3029 clock synthesis and recovery unit is to derive high speed timing signals for SONET/SDH-based equipment. The S3029 is implemented using AMCC's proven Phase Locked Loop (PLL) technology.

The S3029 receives four STS-3/STM-1 scrambled NRZ signals and recovers the clock from the data and generates a 155 MHz transmit clock. The chip outputs a differential PECL bit clock and retimed data. Figure 1 shows a typical network application.

The S3029 utilizes five on-chip PLLs which consist of a phase detector, a loop filter, and a voltage controlled oscillator (VCO). The phase detector compares the phase relationship between the VCO output and the serial data input. A loop filter of S3029 converts the phase detector output into a smooth DC voltage, and the DC voltage is input to the VCO whose frequency is varied by this voltage. A block diagram is shown in Figure 2. There is a single clock multiplier PLL which generates a 155 MHz transmit clock from a 19.44 or 51.84 MHz input.