2.5 Gbps quad limiting amplifier for optical receiver chains
The Maxim MAX3822UCM is a quad limiting amplifier designed for 2.5 Gbps optical network applications. It takes a small-signal input from a photodiode transimpedance amplifier and outputs a clean, amplitude-limited differential signal for clock and data recovery. The four channels let a single device handle multiple fiber lanes or redundant paths on one board. The 48-TQFP exposed pad package (7x7 mm) pulls heat out through the PCB ground plane, which matters when the part runs continuously at line rate.
Active lifecycle — still a current production part
Note the RoHS non-compliant marking — this part uses lead-bearing solder terminations, so verify your assembly line's exemption status before committing the BOM.
Package and thermal — the exposed pad is not optional
The 48-TQFP exposed pad (EP) is the primary thermal path. Solder the pad to a copper land on the PCB with thermal vias to the ground plane — without that connection, junction temperature rises quickly under continuous 2.5 Gbps operation. The 0.5 mm pitch TQFP is a standard footprint for optical modules; layout guides from Maxim's application notes for this family recommend a 4-layer stack with the EP stitched to the inner ground layer.