1.8.1. PMA Features
The transmit features deliver exceptional signal integrity at data rates up to 57.8 Gbps PAM4 / 28.9 Gbps NRZ. Clocking options include ultra-low jitter LC tank-based (ATX) PLLs with optional fractional synthesis capability, channel PLLs operating as clock multiplier units (CMUs), and fractional synthesis PLLs (fPLLs).
- ATX PLL—can be configured in integer mode, or optionally, in a new fractional synthesis mode. Each ATX PLL spans the full frequency range of the supported data rate range providing a stable, flexible clock source with the lowest jitter.
- CMU PLL—when not being used as a transceiver, select PMA channels can be configured as channel PLLs operating as CMUs to provide an additional master clock source within the transceiver bank.
- fPLL—In addition, dedicated fPLLs are available with precision frequency synthesis capabilities. fPLLs can be used to synthesize multiple clock frequencies from a single reference clock source and replace multiple reference oscillators for multi-protocol and multi-rate applications.
On the receiver side, each PMA has an independent channel PLL that allows analog tracking for clock-data recovery. Each PMA also has advanced equalization circuits that compensate for transmission losses across a wide frequency spectrum.
- Variable Gain Amplifier (VGA)—to optimize the receiver's dynamic range
- Continuous Time Linear Equalizer (CTLE)—to compensate for channel losses with lowest power dissipation
- Decision Feedback Equalizer (DFE)—to provide additional equalization capability on backplanes even in the presence of crosstalk and reflections
- On-Die Instrumentation (ODI)—to provide on-chip eye monitoring capabilities (Eye Viewer). This capability helps to optimize link equalization parameters during board bring-up and supports in-system link diagnostics and equalization margin testing
All link equalization parameters feature automatic adaptation using the new Advanced Digital Adaptive Parametric Tuning (ADAPT) circuit. This circuit is used to dynamically set DFE tap weights, adjust CTLE parameters, and optimize VGA gain and threshold voltage. Finally, optimal and consistent signal integrity is ensured by using the new hardened Precision Signal Integrity Calibration Engine (PreSICE) to automatically calibrate all transceiver circuit blocks on power-up. This gives the most link margin and ensures robust, reliable, and error-free operation.
Feature |
Capability |
---|---|
Chip-to-Chip Data Rates |
|
Backplane Support |
Drive backplanes at data rates up to 57.8 Gbps PAM4 / 28.9 Gbps NRZ, including 10GBASE-KR, KP4, CR4, CR2, CEI 56G-LR compliance |
Optical Module Support |
SFP+/SFP, XFP, CXP, QSFP/QSFP28, QSFPDD, CFP/CFP2/CFP4 |
Cable Driving Support |
SFP+ Direct Attach, PCI Express over cable, eSATA |
Transmit Pre-Emphasis |
5-tap transmit pre-emphasis and de-emphasis to compensate for system channel loss |
Continuous Time Linear Equalizer (CTLE) |
Equalization to compensate for system channel loss |
Decision Feedback Equalizer (DFE) |
DFE to equalize backplane channel loss in the presence of crosstalk and noisy environments |
Advanced Digital Adaptive Parametric Tuning (ADAPT) |
Fully digital adaptation engine to automatically adjust all link equalization parameters—including CTLE, DFE, and VGA blocks—that provide optimal link margin without intervention from user logic |
Precision Signal Integrity Calibration Engine (PreSICE) |
Hardened calibration controller to quickly calibrate all transceiver control parameters on power-up, which provides the optimal signal integrity and jitter performance |
ATX Transmit PLLs |
Low jitter ATX (inductor-capacitor) transmit PLLs with continuous tuning range to cover a wide range of standard and proprietary protocols, with optional fractional frequency synthesis capability |
Fractional PLLs |
On-chip fractional frequency synthesizers to replace on-board crystal oscillators and reduce system cost |
Digitally Assisted Analog CDR |
Superior jitter tolerance with fast lock time |
On-Die Instrumentation— Eye Viewer and Jitter Margin Tool |
Simplify board bring-up, debug, and diagnostics with non-intrusive, high-resolution eye monitoring (Eye Viewer). Also inject jitter from transmitter to test link margin in system. |
Dynamic Reconfiguration |
Allows for independent control of each transceiver channel Avalon memory-mapped interface for the most transceiver flexibility. |
Multiple PCS-PMA and PCS-Core to FPGA fabric interface widths |
8, 10, 16, 20, 32, 40, or 64 bit interface widths for flexibility of deserialization width, encoding, and reduced latency |