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 141

2026-11-05 22:33 PST (2026-11-06T06:33:19Z UTC) · commit 3808685 (3808685177ecb2b992c03e7e2f5e28155a5c3d60)

ADOPTED

Shorts locality B: U5 west pad field (5 items). Ripped in box (61.5,-24)-(66,-14.5): I2C_SCL 4 segs, I2C_SDA 13, CDR_CLKP 25, CDR_DATN 6; deleted 4 vias in the field (CDR_CLKP at (63.12,-18.88), (62.62,-18.12), (64.62,-16.12) – the last was the one on U5.8 GND – and CDR_DATN at (65.53,-22.95)). Heal (74 s): all four nets fully reconnected, 7 groups. The I2C vias DRC had paired with U5.6/U5.5 were resolved by the re-lay (their positions in the report were the pads’; the re-laid fanout now clears the column). KiCad DRC referee, exp170 -> exp171: violations 294 -> 283, shorting_items 11 -> 6 (U5 zero; remaining are five single localities), unconnected items 46 -> 45, clearance 42 -> 37, solder_mask_bridge 17 -> 12, copper_edge_clearance 88 unchanged, track_dangling 20 -> 23 (fresh heal stubs).

Nets fully routednot recorded
Pins failednot recorded
Clearance violations77
Unconnected nets31
Audit verdictFAIL

Routes — all copper layers and each layer

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

Top

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Bottom

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