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Simulators >> RF Simulators >> Noise Figure in GoldenGate
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Message started by Mighty Mouse on May 11^th, 2006, 5:44pm

Title: Noise Figure in GoldenGate
Post by Mighty Mouse on May 11^th, 2006, 5:44pm

I am new to the Xpedion software. I am trying to simulate a mixer and compute its noise figure. I have the following questions ...
1. What is the difference between a probe and an output probe?
2. When plotting the noise, it insists that I specify a tone. What is it?
3. How do I plot noise figure?

I would appreciate it if any of you familiar with GG could help me out. I am sure I am missing some key idea and once I get it it will all make sense.

Thanks,
- MM -

Title: Re: Noise Figure in GoldenGate
Post by tubeguy on May 31^st, 2006, 12:29pm

MM:

I suggest using GoldenGate's SSNA (Small Signal Noise Analysis) to calculate the noise figure of your mixer. SSNA seems to be designed more for receiver/transmitter noise simulations, while CR Noise analysis works better for VCOs. That's my experience, at least.

When setting up SSNA, the Input Source can be a vsin, psin, or port, and the Output Probe can be a port, psin, or pmeter from the goldenGateLib. Further down the page, if you select Compute Noise you will be given the option of DSB, SSB, or IEEE noise figure. That's pretty much it! When you run the simulation it will print out the noise figure in the output log, and you can plot it from the results form under Post Process ("NF").

You might also want to do a table of noise contributors. This is hidden at the bottom of the SSNA Options page. I usually select "Types" and then leave all three options checked. You can also select "Expanded" and it will give additional information like flicker/thermal etc. Kind of nice. This table is also accessed under Post Process in the results form ("NCT").

Hope that helps. I didn't answer your questions specifically because it sounds like you are/were trying to use CR, rather than SSNA. Post back if you still need specific answers to those.

JR

Title: Re: Noise Figure in GoldenGate
Post by Mighty Mouse on May 31^st, 2006, 4:51pm

Thanks for the tip Tubeguy. I tried SSNA and I am still confused, perhaps because I am used to SpectreRF and the use model for GG is different. With SpectreRF, I apply the LO and perform a PNoise analysis to compute the noise figure over a range of output frequencies. In this case there is one large tone, the LO, and one small tone, the noise, which is swept over a range of frequencies. GoldenGate asks me to specify two large tones. I know they must be large because it asks for both their frequency and the number of harmonics that are needed. I don't understand why it is asking me to specify two large tones.

Could you suggest how I should set up the SSNA analysis to compute the noise figure of a mixer with 1GHz LO when I want to know the NF over the output frequency range of 1kHz to 1MHz?

Thanks!
- MM -