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Noise measurement for a circuit containing VCO and MIxer

Abhi56

I have a single receiver circuit which has both a VCO and a mixer (from supply to gnd).

I need to simulate Noise figure of this Receiver. Please let me know the correct simulation setup.

This is what is happening when I'm using hb with hbnoise.

In 1st case, I'm giving two tones in hbnoise, one of which being the oscillation frequency fo, and the other being RF frequency frf, provided the sweep type is absolute. But it isn't considering the second source to be possibly an input source and therefore the NF option is disabled. I'm checking the Output Noise in this case.

In the 2nd case, I'm disabling the frf source and doing a 1 tone hb simulation and checking the Output noise again.

Both gave the same graphs for output noise.  

Is this the correct way to measure?

  • Abhi56 said:
    In 1st case, I'm giving two tones in hbnoise, one of which being the oscillation frequency fo, and the other being RF frequency frf, provided the sweep type is absolute. But it isn't considering the second source to be possibly an input source and therefore the NF option is disabled. I'm checking the Output Noise in this case

    I don't understand what you mean here. This should be possible, although possibly unnecessary. If you are simulating a mixer with a VCO input, you would normally have the oscillator as the first tone (and set it to be in oscillator mode since the oscillation frequency needs to be solved for) and then the second tone (the RF input to the mixer) can be a driven signal. You should then be able to compute the noise figure that way - can you show what your forms look like? Also, which version of Virtuoso are you using? (Help->About will give the full sub-version) and ideally which version of Spectre too (appears at the top of the output log when simulating).

    However, you only really need to include the RF signal as a large signal tone if you are expecting the RF signal to be large enough to cause compression, or to see intermodulation with the noise - otherwise it's not that likely to have an effect on the noise figure and can be omitted. That's consistent with what you're seeing when plotting output noise.

    Andrew

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