Altera Cyclone V Device Handbook page 304

CV-53001
2013.05.06
Category
Protocol-Specific
Function
You can AC-couple the receiver to a transmitter. In an AC-coupled link, the AC-coupling capacitor blocks
the transmitter common-mode voltage. At the receiver end, the termination and biasing circuitry restores
the common-mode voltage level that is required by the receiver.
Figure 1-13: AC-Coupled Link with a Cyclone V Receiver
The receiver buffers support the programmable analog settings (CTLE and DC gain), programmable common
mode voltage (RX V
The receiver input buffer receives serial data from the high-speed differential receiver channel input pins
and feeds the serial data to the channel PLL configured as a CDR unit.
Transceiver Architecture in Cyclone V Devices
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Features
Signal Detect Senses if the signal level present at the receiver input is above or
below the threshold voltage that you specified. The detection
circuitry has a hysteresis response that asserts the status signal
only when a number of data pulses exceeding the threshold voltage
are detected and deasserts the status signal when the signal level
below the threshold voltage is detected for a number of recovered
parallel clock cycles. The circuitry requires the input data stream
to be 8B/10B-coded.
Signal detect is compliant to the threshold voltage and detection
time requirements for electrical idle detection conditions as
specified in the PCI Express Base Specification 2.0 for Gen1 and
Gen2 signaling rates. Signal detect is also compliant to SATA/SAS
protocol up to 3 Gbps support.
AC-Coupling
Capacitor
Transmitter
TX
+ –
VCM
AC-Coupling
Capacitor
Note:
1. When you disable OCT, you must implement external termination and off-chip biasing circuitry to
establish the required RX V level.
CM
), OCT, and signal detect function.
CM
Description
Physical Medium
RX
VCM
Physical Medium
(1)
1-17
Receiver Buffer
Receiver
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