Electronics > Projects, Designs, and Technical Stuff
Tracking Generator Alternative: 1GHz Wideband Noise Source
cncjerry:
If you copied the circuit for the noise source off ebay, there was a person that reworked that circuit because it was drawing way to much current at the suggested power supply voltage. If you google around you should be able to find the mods. I have one, made some of the changes but the one in particular where you change the noise source diode I never got around to since I have an SA + TG. I did use it in hot mode and I thought it worked pretty well. If you have a scope with Math + FFT you can put the display in a long retention mode and get a pretty nice plot.
alterbaron:
--- Quote from: LukeW on October 13, 2015, 06:32:54 am ---I put this together recently... haven't tested it yet.
The power supplies are on a separate board, one 30V supply for the avalanche bias (constant current) and a 12V supply for the MMICs.
--- End quote ---
Very pretty! Curious to see how it performs. Do you have a schematic?
What MMICs did you use, and what did you use for the noise source proper?
AF6LJ:
Yes this looks really interesting.
LukeW:
--- Quote from: alterbaron on October 14, 2015, 10:55:09 pm ---
--- Quote from: LukeW on October 13, 2015, 06:32:54 am ---I put this together recently... haven't tested it yet.
The power supplies are on a separate board, one 30V supply for the avalanche bias (constant current) and a 12V supply for the MMICs.
--- End quote ---
Very pretty! Curious to see how it performs. Do you have a schematic?
What MMICs did you use, and what did you use for the noise source proper?
--- End quote ---
Basically as shown here:
http://www.edn.com/design/test-and-measurement/4358938/Zener-diode-and-MMICs-produce-true-broadband-noise
It's an ordinary 24V zener, not a dedicated noise diode. A constant-current source is used to bias the diode.
Three MiniCircuits MMICs are used as per the schematic.
I've added an 8V regulator to supply the MMICs, and changed their bias resistors accordingly, and moved the "high" voltage boost converter circuit for the diode off to a separate board.
This allows experimentation with different voltages, as well as keeping power dissipation in the bias resistors fairly small.
Hopefully the parasitic inductances etc are OK with 0603 passives used throughout... I didn't think it was worth bothering with 0402. (A couple of 0805s are used for MMIC biasing due to power constraints.)
JeffEurope:
Hello!
I have a question. I try the HP346B noise source on the spectrum analyzer - as the "tracking source". After connecting to +28V pulse DC voltage, the noise level on spectrum analyzer has not changed. Is it normal?
Thank you for explanations!
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