ORSPI4 Datasheet, PDF (187/263 Pages) Lattice Semiconductor – Dual SPI4 Interface and High-Speed SERDES FPSC

Lattice Semiconductor
ORCA ORSPI4 Data Sheet
Input Eye-Mask Characterization
Figure 97 provides an eye-mask characterization of the SERDES receiver input. The eye-mask is specified below
for two different eye-mask heights. It provides guidance on a number of input parameters, including signal ampli-
tude and rise time limits, noise and jitter limits, and P and N input skew tolerance. Almost all detrimental character-
istics of transmit signal and the interconnection link design result in eye-closure. This, combined with the eye-
opening limitations of the line receiver, can provide a good indication of a link’s ability to transfer data error-free.
The Clock and Data Recovery (CDR) portion of the ORSPI4 SERDES receiver has the ability to filter incoming sig-
nal jitter that is below the clock recovery PLL bandwidth (about 3 MHz). The eye-mask specifications of Table 70
are for jitter frequencies above the PLL bandwidth of the CDR, which is a worst case condition. When jitter occurs
at frequencies below the PLL bandwidth, the receiver jitter tolerance is significantly better. For this case error-free
data detection can occur even with a completely closed eye-mask.
Figure 97. Receive Data Eye-Diagram Template (Differential)
T
V
1.2 V
H
UI
Table 70. Receiver Eye-Mask Specifications¹
Parameter
Conditions
Value
Unit
Input Data
Eye Opening Width (H) @ 3.125 Gbps
V=175 mV diff¹
0.55
UIP-P
Eye Opening Width (T) @ 3.125 Gbps
V=175 mV diff¹
0.15
UIP-P
Eye Opening Width (H) @ 3.125 Gbps
V=600 mV diff¹
0.35
UIP-P
Eye Opening Width (T) @ 3.125 Gbps
V=600 mV diff¹
0.10
UIP-P
Eye Opening Width (H) @ 2.5 Gbps
V=175 mV diff¹
0.42
UIP-P
Eye Opening Width (T) @ 2.5 Gbps
V=175 mV diff¹
0.15
UIP-P
Eye Opening Width (H) @ 2.5 Gbps
V=600 mV diff¹
0.33
UIP-P
Eye Opening Width (T) @ 2.5 Gbps
V=600 mV diff¹
0.10
UIP-P
1. With PRBS 2^7-1 data pattern, 10 MHz sinusoidal jitter, all channels operating, FPGA logic active, REFCLK jitter
of 30 ps., TA = 0^oC to 85^oC, 1.425 V to 1.575 V supply.
187