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 87

2026-11-05 01:52 PST (2026-11-05T09:52:16Z UTC) · commit d79fd23 (d79fd232350a5bdda5cfea6066460f3cb1b0c9ad)

ADOPTED

Thread sweep 1 (thread_far, all 35 nets, exp38 -> exp39): 9 pair merges – APD_K (0.09 gap), CDR_NIN (1.46), CMP_QN (0.17), GND (0.25), HV_DAC (0.08, net complete), HV_FBX (0.33), HV_RAW (1.16), HV_SEC (8.46, 12 segs 2 vias, net complete), XI (0.78, net complete). Most ‘unconnected’ groups were hairline stub gaps the audit grouping cannot join. Cost: HV_SEC’s thread ripped 6 foreign items; violations 67 -> 75 and HV_RAW’s merge was offset by a rip split (still 4 groups) – rip victims are repaid by heal/thread rounds next. Refusals recorded: anchor-walled (+3V3A, +3V3D_CDR, +5V, CC2, PHY_1V8/A, SLICEN), lattice no-thread (HV_INTVCC, HV_SS, SET_P), pairs > 15 mm (ULPI x8, USB_RST, CAP_DATA, CDR_PIN, CDR_SQUELCH, CF2, DP_PHY, FLY_PRI, HV_SHDN). Audit: nets 35 -> 32, violations 75.

Nets fully routednot recorded
Pins failednot recorded
Clearance violations75
Unconnected nets32
Audit verdictFAIL

Routes — all copper layers and each layer

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

Top

Pass 87 — top

Bottom

Pass 87 — bottom

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