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 139

2026-11-05 22:16 PST (2026-11-06T06:16:28Z UTC) · commit 1ba94ed (1ba94ed1fcde11e82c2b33389d1eba50c34daed8)

ADOPTED

Shorts locality A: east strip (X1/LED column/ULPI fanout), 16 items + LED victim repaid. Ripped in box (84.5,5)-(94.5,19): +3V3D 20 segs, ULPI_D4 17, ULPI_D6 25, LED_STAT 19 (LED_PWR_K/LED_STAT_A had zero segments – never routed); deleted 2 stray vias in the LED field (LED_PWR_K at (89.875,8.125), LED_STAT at (89.125,13.625)). Heal (116 s): +3V3D reconnected both groups, re-laid on In2.Cu EAST of the D7/R44 column (was: F.Cu trunk through D7.2 and R44.2 pads); ULPI_D4/D6 reconnected around X1.2; LED_PWR_K CONNECTED D6.1->R44.1 down the west side of the column (victim repaid). LED_STAT D7.1 and LED_STAT_A D7.2 STILL isolated – pads open but the strip is crossed by the CDR_CLKP/CLKN diagonals; next mechanism is a local rip of the pair + heal LEDs first. KiCad DRC referee, exp165 -> exp166: violations 320 -> 297, shorting_items 27 -> 11 (east strip zero), solder_mask_bridge 31 -> 17, clearance 44 -> 42, unconnected items 48 -> 47. Regressions noted: copper_edge_clearance 80 -> 85 (re-laid strip routes run nearer the east edge; that class is next in queue), track_dangling 21 -> 25 (fresh heal stubs).

Nets fully routednot recorded
Pins failednot recorded
Clearance violations87
Unconnected nets32
Audit verdictFAIL

Routes — all copper layers and each layer

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

Top

Pass 139 — top

Bottom

Pass 139 — bottom

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