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 108

2026-11-05 08:54 PST (2026-11-05T16:54:46Z UTC) · commit 036be9c (036be9c586201a1e4cfab0ab553eee5b776cf093)

ADOPTED

Heal campaign exp79->exp81 over 30 non-knot nets (heal_nets, results/heal-exp81.log). DELTAS: nets 38->33, violations 87->120. Joins: HV_R31A, HV_FBX, CDR_DATP, ULPI_DIR connected outright; APD_K 6->5 groups (C33/C4/R30 cluster merged). Violation delta +33 concentrated in ONE join: 32 lines from heal’s HV_RAW B.Cu surface diagonal vs the GND pours at the 1.0 mm HV class, +1 XI vs a new CDR_DATP via at (87.125,16.625). HV_RAW’s join exceeds the acceptance bound; it is ripped and re-approached (In2 bridge + D9 pour notch) in the next pass. All other joins landed clean (0 new violations). Still isolated after heal (residue for hand work): SLICEN U4.7, SET_P U13.7, +3V3D_CDR U4.12 group, +5V U11/U7.4 groups, PHY_1V8 U7.15/U7.26, PHY_1V8A C23.1, APD_K R31.1/D1.5/R47.2/RJ2.2, CC2 J1.B5 group, +3V3A U7.6/16/25, U6/U7 single pads (CAP_CLK, CDR_LOL, CDR_SQUELCH, HV_EN, HV_SHDN, SWDIO, USB_RST, VCAP1), CDR_PIN U4.5 group, CF2 C15.2 group, DM_PHY/DP_PHY U7 pads, RBIAS U7.32, XI/XO X1-site groups.

Nets fully routednot recorded
Pins failednot recorded
Clearance violations120
Unconnected nets33
Audit verdictFAIL

Routes — all copper layers and each layer

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

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Pass 108 — top

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Pass 108 — bottom

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