The DS160UP822 is a linear redriver that can be used to extend channel reach of a UPI link. Normally, PCIe-compliant TX and RX are equipt with signal-conditioning functions and can handle channel losses of up to 28 dB at 8 GHz. With the DS160UP822 in the link, the total channel loss between two CPUs can be up to 42 dB at 8 GHz.

Figure 8-3 shows an electric link that models a single channel of a UPI link and eye diagrams measured at different locations along the link. The source that models a UPI TX sends a 16 Gbps PRBS-15 signal with P7 presets. After a transmission channel with –30 dB at 8 GHz insertion loss, the eye diagram is fully closed. The DS160UP822 with its CTLE set to the maximum (18 dB boost) together with the source TX equalization compensates for the losses of the pre-channel (TL1) and opens the eye at the output of the device.

The post-channel (TL2) losses mandate the use of UPI RX equalization functions such as CTLE and DFE that are normally available in receivers.

Figure 8-3 UPI 2.0 Link Reach Extension Using DS160UP822