HC4GX15 Datasheet, PDF (295/668 Pages) Altera Corporation – HardCopy IV Device Handbook

Chapter 1: HardCopy IV GX Transceiver Architecture
1–31
CMU Channels
■ From CMU channel0 on the other transceiver block on the same side of the
device through the ×N clock line (×N_Top or ×N_Bottom clock line). If you
configure a CMU channel in Basic (PMA-Direct) ×N mode, you can use this
clocking option
■ From one of the ATX PLL blocks on the same side of the device through the ×N
clock line (×N_Top or ×N_Bottom clock line)
Input Reference Clocks for the Receiver CDR
When a CMU Channel is configured as a transceiver channel, there are multiple
sources of input reference clocks for the receiver CDR:
1. From adjacent REFCLKs within the same transceiver block, if the adjacent CMU
Channel is not used as a transceiver channel
2. From the REFCLK of adjacent transceiver blocks on the same side of the device, if
the corresponding CMU channels are not used as transceiver channels. For
REFCLK connections to the CMU channel from the global clock lines and PLL
cascade network, refer to Table 1–4 on page 1–36.
Clocks for the Receiver Deserializer
The CDR provides the high-speed serial and low-speed parallel clock to the receiver
deserializer high-speed clock. The receiver deserializer is provided by the high-speed
serial and parallel clock of the CDR from the recovered data. There are multiple
sources to provide input reference clocks to the CDR of the CMU channel.
Other CMU Channel Features
The CMU channels provide the following features:
■ Analog control options—Differential Output Voltage (V_OD), pre-emphasis,
equalization, and DC gain settings present in the regular channels are also
available in the CMU channels.
■ On-chip termination (OCT)—CMU channels can have an on-chip termination
feature. The allowed termination values are the same as regular channels (85, 100,
120, 150 Ω).
■ Loopback—The available loop back options are serial, reverse serial (pre-CDR),
and reverse serial (CDR) loopback.
For more information about analog controls and on-chip termination, refer to
“Transmitter Output Buffer” on page 1–52, and “Receiver Input Buffer” on page 1–59.
For more information about loopback, refer to “Loopback Modes” on page 1–188.
Dynamic Reconfiguration
You can dynamically reconfigure the analog controls of the CMU channel using the
dynamic reconfiguration controller.
f For more information about dynamic reconfiguration options, refer to the
HardCopy IV GX Dynamic Reconfiguration chapter in volume 3 of the HardCopy IV
Device Handbook.
© June 2009 Altera Corporation
HardCopy IV Device Handbook Volume 3