Montage Technology PCIe Retimer Chips

PCIe retimers and redrivers both improve signal integrity but work differently. Redrivers use analog equalization to boost signal strength - they're simpler and lower cost but only address amplitude loss. Retimers recover the digital data and retransmit a clean signal - they address both amplitude and timing (jitter) issues and can reset jitter budgets. Use redrivers for short channel extensions (< 12 inches) with minimal jitter concerns. Use retimers for longer channels, complex topologies, or when jitter accumulation is a concern. For PCIe Gen4 and Gen5 at full channel lengths, retimers are generally preferred for reliable operation.

Use retimers for Gen4/Gen5 long channels or complex topologies. Redrivers may suffice for short extensions on Gen3.

PCIe retimer chips are essential when signal integrity challenges limit PCIe link performance. Use retimers when: PCB trace lengths exceed 8-10 inches for PCIe Gen4 or Gen5 signals

routing through connectors or backplanes introduces significant insertion loss

crosstalk and reflections degrade signal quality

you need to extend PCIe reach while maintaining compliance. Montage's M88RT series retimers support PCIe Gen4 (16 GT/s) and Gen5 (32 GT/s) with advanced equalization to compensate for channel loss. Retimers are commonly used in servers, storage systems, and networking equipment where PCIe signals must traverse complex backplanes or reach distant endpoints.

Use our PCIe Signal Integrity Calculator to determine if your channel requires retiming. Contact LiTong FAEs for channel analysis.

Determine retimer need through channel analysis: Calculate total insertion loss including traces, connectors, and vias. Compare against PCIe specification limits. For Gen4, typical limit is -28dB at 8GHz

for Gen5, -36dB at 16GHz. If your channel exceeds these limits, a retimer is likely needed. Use IBIS-AMI models to simulate eye diagrams and verify margin. Montage provides channel analysis tools and FAE support for this evaluation.

Perform channel analysis using IBIS-AMI models. Contact LiTong FAEs for assistance with retimer selection.

Retimer placement depends on channel characteristics. General guidelines: Place at the midpoint of long channels for optimal performance. Avoid placing near noisy components. Ensure adequate power supply filtering at the retimer location. Provide proper thermal management. For very long channels, multiple retimers may be needed - space them evenly. Consider signal routing complexity when selecting placement. Montage FAEs can review your layout and recommend optimal placement.

Place retimers at channel midpoints with proper power and thermal management. Contact LiTong for placement review.

PCIe retimers require clean power supplies for optimal performance. Requirements vary by device but typically include: Core voltage (0.85V typical for Gen5), I/O voltage (1.8V or 3.3V), and analog supply for PLL. Power supplies should have low noise and adequate decoupling. Follow manufacturer recommendations for decoupling capacitor placement and values. Power supply noise can directly impact jitter performance, so proper filtering is essential.

Follow Montage's power supply recommendations exactly. Implement adequate filtering and decoupling.