V-Series Transceiver PHY IP Core User Guide

ID 683171
Date 7/26/2022
Public
Document Table of Contents

12.3. Deterministic Latency PHY Delay Estimation Logic

This section provides the equations to calculate delays when the Deterministic Latency PHY IP core implements CPRI protocol.

This section provides the equations to calculate delays when the Deterministic Latency PHY IP Core implements CPRI protocol. CPRI defines the radio base station interface between network radio equipment controllers (REC) and radio equipment (RE) components.

For RE

Note:

In single width (PMA =10) mode, add one UI delay per value of rx_std_bitslipboundaryselect. For constant round-trip delay (RX+TX), set tx_std_bitslipboundaryselect <= (5'd9 - rx_std_bitslipboundaryselect).

In double width (PMA =20) mode, add one UI delay per value of (5'd9 - rx_std_bitslipboundaryselect). For constant round-trip delay (RX+TX), set tx_std_bitslipboundaryselect <= rx_std_bitslipboundaryselect.

For REC

For Round Trip Delay

Total Delay Uncertainty

Round trip delay estimates are subject to process, voltage, and temperature (PVT) variation.

Table 162.  TX PCS Total LatencyThis table shows the total latency through the TX PCS in parallel clock cycles with the byte serializer/deserializer turned off. The TX compensation FIFO is in register mode.
PCS Datapath Width TX Phase Comp FIFO Serializer 8B/10B Bitslip (tx_std_bitslipboundaryselect)9 Total TX Parallel Clock Cycles
Byte Serializer/Deserializer Turned Off
8 bits 1.0 1.0 1.0 0 3.0
16 bits 1.0 1.0 1.0 0 3.0
Byte Serializer/Deserializer Turned On
16 bits 1.0 0.5 0.5 0 2.0
32 bits 1.0 0.5 0.5 0 2.0
Table 163.  RX PCS Total Latency The RX compensation FIFO is in register mode. When the byte serializer/deserializer in turned on, the latency through is function depends on the location of the alignment pattern. When the alignment pattern is in the upper symbol, the delay is 0.5 cycles. When the alignment pattern is in the lower symbol, the delay is 1.0 cycles.

PCS Datapath Width RX Phase Comp FIFO Byte Ordering Deserializer 8B/10B Word Aligner 11 10 Total RX Parallel Clock Cycles 10 11
Byte Serializer/Deserializer Turned Off
8 bits 1.0 1.0 1.0 1.0 4.0 8.0
16 bits 1.0 1.0 1.0 1.0 5.0 9.0
Byte Serializer/Deserializer Turned On
16 bits 1.0 1.0 0.5 or 1.0 0.5 2.0 5.0 or 5.5
32 bits 1.0 1.0 0.5 or 1.0 0.5 2.5 5.5 or 6.0
Table 164.  PMA Datapath Total LatencyThe latency numbers in this table are actual hardware delays .
Device RX PMA Latency in UI TX PMA Latency in UI
PCS to PMA Width 10 bits PCS to PMA Width 20 bits PCS to PMA Width 10 bits PCS to PMA Width 20 bits
Cyclone V 26 31 42 62
Arria V 34 49 52 82
Arria V GZ 26 31 53 83
Stratix V 26 31 53 83
9 This latency is calculated assuming that the optional tx_std_bitslipboundaryselect is set to zero. Add one UI of latency per value of this port. For example, if tx_std_bitslipboundaryselect is set to one, add one UI of latency to the total.
10 When the word aligner is in manual mode, and the byte deserializer is turned off, add x UI of latency to the total latency if rx_std_bitslipboundaryselect is outputting x. For constant RX + TX latency, set tx_std_bitslipboundaryselect = 5’d9 – rx_std_bitslipboundaryselect.
11 When the word aligner is in manual mode, and the byte serializer is turned on, add (19-x) UI of latency to the total latency if rx_std_bitslipboundaryselect is outputting x. For constant RX + TX latency, set tx_std_bitslipboundaryselect = rx_std_bitslipboundaryselect.