Zynq UltraScale+ Device Technical Reference Manual (UG1085)

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2.4 English

The receiver is fundamentally a serial-to-parallel converter, changing the incoming bit-serial differential signal into a parallel stream of words, each 16, 20, 32, 40, 64, or 80 bits in the GTH transceiver or 16, 20, 32, 40, 64, 80, 128, or 160 for the GTY transceiver. This allows a trade-off of internal datapath width against logic timing margin. The receiver takes the incoming differential data stream, feeds it through the programmable DC automatic gain control, linear and decision feedback equalizers (to compensate for PC board, cable, optical and other interconnect characteristics), and uses the reference clock input to initiate clock recognition. There is no need for a separate clock line. The data pattern uses non-return-to-zero (NRZ) encoding and optionally ensures sufficient data transitions by using the selected encoding scheme. Parallel data is then transferred into the device logic using the RXUSRCLK clock. For short channels, the transceivers offer a special low-power mode (LPM) to reduce power consumption by approximately 30%. The receiver DC automatic gain control and linear and decision feedback equalizers can optionally auto-adapt to automatically learn and compensate for different interconnect characteristics. This enables even more margin for tough 10G+ and 25G+ backplanes.