Arria® V Device Handbook: Volume 2: Transceivers

ID 683573
Date 5/29/2020
Public
Document Table of Contents

2.2.2.2. Bonded Channel Configurations

The channel clock path for bonded configurations is driven by the x6 and xN clock lines.

Table 45.   Clock Path for Bonded Configurations The following table describes the clock path for a bonded configuration with ATX PLL, CMU PLL, or fPLL as TX PLL using various clock lines.
Clock Line Transmitter PLL Clock Path
x6, xN ATX PLL26 CMU PLL » central clock divider » x6 » xN » serializer
CMU CMU PLL » central clock divider » x6 » xN » serializer 25
fPLL fPLL » x1_fPLL » central clock divider » x6 » serializer 25
x6 PLL Feedback Compensation 27 ATX PLL 26 ATX PLL » central clock divider » x6 » serializer
CMU CMU PLL » central clock divider » x6 » serializer
Figure 60.  Four Bonded Transmitter Channels Driven by CMU PLL using x6 and xN Clock Lines Across Multiple Transceiver Banks


Note: When channel PLL is configured as a CMU PLL to drive the local clock divider or the central clock divider of its own channel, the channel PLL cannot be used as a CDR. Without a CDR, the channel can be used only as a transmitter.
Figure 61. Four Bonded Transmitter Channels Driven by fPLL using x6 Clock Line Within a Transceiver Bank


Note:
  • When using the fPLL to drive bonded channels, assign logical channel 0 to the channel where the central clock divider is used for fPLL clocks to access the x6 clock line. Using the preceding figure as an example, assign tx_serial_data[0] to the transmitter channel 4 pin location.
  • For xN bonded configurations, the channel where the central clock divider resides (ch 1 or ch 4) can be used as a data channel as the parallel clock can be generated in this channel.

Bonded Channel Configurations Using the PLL Feedback Compensation Path for GZ Devices

You can bond channels across multiple banks by using the PLL feedback compensation path.

The PLL feedback compensation path loops the parallel clock, which is used by the PCS blocks, back to the transmitter PLL. The PLL feedback compensation path synchronizes the parallel clock used to clock the PCS blocks in all transceiver banks with the refclk. You can use the PLL feedback compensation path to reduce channel-to-channel skew, which is introduced by the clock divider in each transceiver bank.

To bond channels using the PLL feedback compensation path, the input reference clock frequency used by the transmitter PLL must be the same as the parallel clock that clocks the PCS of the same channel.

Note: If the input reference clock frequency is not equal to the parallel clock frequency, use a fractional PLL to synthesize an input reference clock with the same frequency as the parallel clock.
Figure 62. Three Transceiver Bank Channels Bonded Using the PLL Feedback Compensation Path for GZ Devices
Note:
  • Every transceiver bank with a bonded channel configured using the PLL feedback compensation path consumes a transmit PLL.
  • fPLL does not support PLL feedback compensation when used as a TX PLL.

Transceiver Channel Placement Guidelines for fPLL in Transmit PLL Bonded Configuration (Except GZ Devices)

The fPLL as transmit PLL, when configured in bonded configuration, has placement restrictions. All channels need to be placed within one transceiver bank. A link cannot span across two banks. The channel placement must also be contiguous.

25 Bonded channels within same bank as the TX PLL are driven by clocks from the x6 clock line, and channels in other banks are driven from the xN clock line.
26 ATX PLL is available for GZ devices only.
27 x6 PLL Feedback Compensation is available for GZ devices only.