Altera Cyclone V Device Handbook page 300

CV-53001
2013.05.06
Category
Protocol-Specific
Function
Transmitter Buffer Features and Capabilities
Table 1-5: Transmitter Buffer Features
Feature
Programmable Differential Output
Voltage (V )
OD
Programmable Pre-Emphasis
On-Chip Biasing for Common-Mode
Voltage (TX V
Differential OCT
Transmitter Output Tri-State
Receiver Detect
Transceiver Architecture in Cyclone V Devices
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Features
Transmitter
Output Tri-State
Receiver Detect
Up to 1200 mV of differential peak-to-peak output voltage
Support first Updated the Post Tap Pre-emphasis setting
0.65 V
)
CM
85, 100, 120, and 150 Ω
Supports the electrical idle function at the transmitter as required by
the PCIe Base Specification 2.0 for Gen1 and Gen2 signaling rates
Supports the receiver detection function as required by the PCIe Base
Specification 2.0 for Gen1 and Gen2 signaling rates
Transmitter Buffer Features and Capabilities
Enables the transmitter differential pair voltages to be held
constant at the same value determined by the TX V
with the transmitter in the high impedance state.
This feature is compliant with differential and common-mode
voltage levels and operation time requirements for transmitter
electrical idle, as specified in the PCI Express Base Specifica-
tion 2.0 for Gen1 and Gen2 signaling rates.
Provides link partner detection capability at the transmitter
end using an analog mechanism for the receiver detection
sequence during link initialization in the Detect state of the
PCIe Link Training and Status State Machine (LTSSM) states.
The circuit detects if there is a receiver downstream by
changing the transmitter common-mode voltage to create a
step voltage and measuring the resulting voltage rise time.
For proper functionality, the series capacitor (AC-coupled
link) and receiver termination values must comply with the
PCI Express Base Specification 2.0 for Gen1 and Gen2
signaling rates. The circuit is clocked using fixedclk and
requires an enabled transmitter OCT with the output tri-
stated.
Capability
Description
Altera Corporation
1-13
level
CM