sfp – anderswallin.net

SFP-board in a box

Update: first production batch being tested in the lab 2020-12-17:

By popular demand, I've worked with Aivon to put my simple 'SFP2SMA' board (https://github.com/aewallin/SFP2SMA_2018.03) in a box, using an external Meanwell (+12V, -12V, +5V) PSU with a 5-pin DIN8 plug (model GP25A13D-R1B, Digikey 1866-1826-ND). The board can be used for simple frequency-transfer experiments together with almost any SFP-transciever. The TX SMA-connector is an input, and applies the waveform to the TX-pins of the SPF, producing modulated optical output. The dual RX SMA-connectors are driven by the SFP RX-pins, with some gain applied to produce around +10 dBm square-wave into a 50R load.

The front panel has three SFP status-LEDs: TX-fault (I've never seen this, but apparently the SFP should report if the TX-laser fails), RX LOS (loss of signal, active if you unplug the fiber), and mod_abs (module absent, active if no SFP is plugged)

After some adjustments to gains and component values the frequency-response is flat within 3 dB out to ca 400 MHz, and the ADEV looks reasonable at ca 1e-13/tau(s) (red datapoints in the plot below). These measurements were done with a CWDM SFP and a 2m single-mode loopback-fiber.

The box is a Hammond 1455L1201 (120 mm x 103 mm x 31 mm), with custom front and back panels.

Front panel with TX, SFP, and dual RX outputs

SFP loopback board

A simple SFP loopback board that loops back any received signal on the SFP RX-pins to the TX-pins. There's a voltage divider probing the signals, and an ONET1191P limiting amplifier provides amplified differential outputs, for probing the signal going through the SFP.

https://github.com/aewallin/SFP-Loopback-Board

Simple SFP-breakout-board

Designed in 2018, but only now uploaded to github, a simple SFP breakout board for playing around with SFP or SFP+ transcievers.

In contrast to earlier boards, this one has no op-amps or transformers on the TX/RX lines, and bandwidth seems to be good enough for 1Gbit/s at least.

https://github.com/aewallin/SFP-Breakout-Board

SFP Connector

20pin SMD connector + cage for SFP transceiver.

500 MHz SFP-board (v4)

This is the fourth version of an interface board to Small Form Factor Pluggable optical transcievers (SFPs) with a bandwidth of >500 MHz. These are useful for various time/frequency experiments, with a measured frequency stability of <1e-13 @ 1s (in 0.5 or 5 Hz bandwidth) - perhaps slightly depending on what SFP is used. The SFP allows sending the signal along a single-mode fiber for 1-100 km easily.

ADT2-1T converts to and from differential signals while LMH6702 op-amps provide 3 dB gain. There are parallel outputs on the RX pins. The current-draw on +3V3 by the SFP is quite high - usually requiring heat-sinking on the voltage-regulator

KiCad files available on request.