Research Lab Technologist
"Giga PD" 8GHz Amplified PhotoDiode
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NOTICE: This webpage and associated files is provided for reference only. This is not a kit site! It is a collection of my work here at the University of Toronto in the Physics department. If you are considering using any schematics, designs, or anything else from here then be warned that you had better know something of what you are about to do. No design is guaranteed in any way, including workable schematic, board layout, HDL code, embedded software, user software, component selection, documentation, webpages, or anything.
All that said, if it says here it works then for me it worked. To make the project work may have involved undocumented additions, changes, deletions, tweaks, tunings, alterations, modifications, adjustments, waving of a wand while wearing a pointy black hat, appeals to electron deities and just plain doing whatever it takes to make the project work.
Started April 2010 for Amir Feizpour in Aephraim's lab. The Giga Pd is a 8GHz amplified photodiode (PD) to be used as the front end of the ChromaMatic2 laser tuning. Although these are available commercially, we keep our arm and leg and make them for 5-10% of the cost.
The core of the device is a JDSU PL-SxR-00-Sx3-C6 ROSA (Receiver Optical SubAssembly). Although optimized for the 850nm band, it works well at 780nm. The output is differential analog. Unfortunately, useable wideband transformers/baluns for 1-8GHz are not available. One output is simply terminated, the other is capacitor coupled to an SMA connector which plugs into a Minicircuits amplifier ZX60-8008E-S+. Even this low powered amp's output has to be attenuated by 6dB (such as Mini-Circuits' VAT-6+) before connecting to the ChromaMatic2. The +3.3V supply is from a linear regulator using the same +12V as the amplifier. Note that there were serious overshoot problems at power up with the LM1086xT-3.3 linear regulator which destroyed two ROSAs, see the screen captures for details.
For the record, the whole PD and amplifier assembly was put into a Hammond 1591BSBK box, with holes for the fibre, SMA cable and two bannana plugs for the signal strength monitor. Power is from a 12V/0.5A CUI Inc EPS120050-P1P wall wart.
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