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My ADS circuit oscillates but ha no harmonics.

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skatefast08

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What could I possibly be doing wrong with my harmonic simulation in ADS, when my transient has an oscillation between -500 mV to 500 mV. Shouldn't I get a harmonic magnitude at the frequency of the oscillation?
 

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That signal may not be large enough to bring in any diode
nonlinearities, and then you would not generate those kinds
of "squaring / clipping" harmonics.

Try +/1V and see what changes.
 

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How you have organized your HB set-up ??
Post it here.
Because HB set-up for oscillators is little bit tricky. You should define well some important HB metrics otherwise HB might not be converged or even give errors.
 

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I actually got it to work. I guess the reason was that I put in the wrong fundamental frequency in for the harmonic balance. I put in 1 GHz, when its supposed to be around 4 and 5 GHz. Below is the 1 GHz harmonic balance simulation and the 2nd picture is the 5 GHz harmonic balance. I also don't understand how I still get an oscillator when my phase shift at 5 GHz is only 43 degrees when doing an AC simulation see 3rd image for this.

Lastly, I want to vary the frequency by varying a transmission line configuration for a resonator. how would you go about this? Also how do you get an ocillator when your phase shift is only 43 degrees?

Thanks

1680651484165.png


1680708379666.png


1680710523475.png

--- Updated ---

Note: Transistor being used is: pf_hp_ATF21170_19931015
 
Last edited:

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Hi BigBoss, I actually used an RFC this time, used an emitter resistor to lower my amps to get 20 mA and used a 3VDC power supply. I actually get no harmonics now, since I used an RFC. I dont understand why I get a transient with about 9 GHz and I used a 9GHz fundamental frequency, but no magnitude like last time.
1680726681049.png
 

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1680803793443.png


Still no harmonics, but I got them oscillations going ;). Same circuit as before, but instead using EM simulation for the circuit board
 

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