HB simulation of two input signal

Two problems that I can immediately spot:

1. You've not specified a pulse width for your pulse source, and so that (might) mean that the duty cycle is undefined (I've not got access to the tools right now so I can't check whether there is a default pulse width as a ratio of the period. I expect you'd probably want to specify the pulse width as 50p)
2. You need to specify the number of harmonics for the second tone. How many is appropriate will depend on the harmonic content of the circuit response - so how non-linear the response is to the 10.1GHz tone. You can't leave it blank (I think) - I suspect if it's blank, it's only specifying a single tone in the netlist (looking at the hb line in the input.scs would make that clear).

Regards,

Andrew.

So if i understand you corretly, if i have two input sources then in the HB i choose two tones

IN1=square wave  f1=1/T=10.1Ghz

IN2=sinus f2=10 Ghz

OUT=0.1GHZ

so what  fundamental do we choose in the HB simulation?

Thanks

Your tones you specified above were the other way around - the square wave was 10GHz, and the sine wave was 10.1GHz. You should specify two tones on the hb form, with the square wave (since it's the most nonlinear) being tone 1. 

There's no need (nor should you, because that would be bad) to specify the output frequency as a tone, because that arise from the 1*10.1GHz-1*10GHz (or 1*1GHz-1*10.1GHz). So it's a harmonic combination of first order tones of the two input tones.

You don't have a single fundamental in the HB simulation - you specify each tone and the number of harmonics to simulate of each, and the harmonic balance outputs the matrix of harmonic combinations up to the max harms of each tone.

Regards,

Andrew.

I understand so one fundamental is 10Ghz and the other is 10.1Ghz and for each   fundamental i choose 5 harmonics.

i need  my OUTPUT to be the harmonics of a differential signal, but when i choose DIRECT PLOT , i can choose only one NET  on the schematics as shown bellow.

How can i get it to show me a differential signal harmonic as shown bellow?

Thanks

5 harmonics may not be enough for the square wave signal - you might be better off leaving that as auto (you can only use auto on the first tone). You need to use Direct Plot->Main Form and then you can pick differential signals.

It seems as if you really need some training. At the very least, I'd suggest you take a look at the workshops that are in the SPECTRE/MMSIM releases - there's a compressed tar file in <SPECTREinstDir>/tools/spectre/examples/SpectreRF_workshop/rfworkshop.tar.Z - if you unpack this in your workspace with "tar xvfz rfworkshop.tar.Z" you'll find there's a doc directory with PDFs explaining how to simulate and measure various things for LNAs, mixers, oscillators and PAs. There's also the SpectreRF Theory manual in the documentation. This is not a substitute for training, but it's a good start.

Regards,

Andrew.