Description
Features
Category
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.
Signal Detect
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
+
–
+
–
TX
VCM
Differential
Termination
Transmitter
Receiver
RX
VCM
Differential
Termination
Physical Medium
Physical Medium
AC-Coupling
Capacitor
AC-Coupling
Capacitor
(1)
Note:
1. When you disable OCT, you must implement external termination and off-chip biasing circuitry to
establish the required RX V
CM
level.
The receiver buffers support the programmable analog settings (CTLE and DC gain), programmable common
mode voltage (RX V
CM
), OCT, and signal detect function.
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.
Altera Corporation
Transceiver Architecture in Cyclone V Devices
1-17
Receiver Buffer
CV-53001
2013.05.06