PDLVDS-RX — photodiode LVDS receiver

Clean-room receiver for the Miniscope Zero optical uplink: Excelitas C30737LH Si APD → OPA657 TIA → LMH7220 comparator (LVDS out, DAC-set threshold) → ADN2813 CDR → STM32H723 + USB3300 USB-HS. Design target: 50 Mbps line rate, 8b/10b (40 Mbps payload); the paper's mode: 8 Mbps Manchester (16 Mbaud), as transmitted. LT3757 flyback APD bias 150–420 V. USB-C powered; verify on any laptop over USB, no FPGA attached.

Pass 135

2026-11-05 21:46 PST (2026-11-06T05:46:50Z UTC) · commit 617e1ea (617e1ea713ffc8de6c0124114affa94c8202860c)

ADOPTED

U5 fanout rip-and-relay, first locality proven: CDR_DATP. Ripped the 6 CDR_DATP segments intersecting the U5 west pad-field box (x 61.5..66, y -24.5..-20) – the escape zigzag that crossed U5.+3V3D pad 4 three times and CAP_DATA – then re-laid with heal_nets (KiCad 8 compat copies in scratch/heal8/: wx preambles stripped, run under xvfb; hw/ originals untouched). Heal reported 2 groups connected. KiCad DRC referee: violations 416 -> 411, shorting_items 57 -> 54 (zero CDR_DATP shorts remain), clearance 66 -> 65, unconnected items 50 UNCHANGED, no class regressed. The mechanism (rip the net’s copper in the pad-field box, heal, DRC-verify) is now proven for the U5 locality; +3V3D’s U5 distribution (16 GND-pad shorts + CLKP/CLKN) is the next and largest application.

Nets fully routednot recorded
Pins failednot recorded
Clearance violations138
Unconnected nets35
Audit verdictFAIL

Routes — all copper layers and each layer

F.Cu In1.Cu In2.Cu B.Cu

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