I tried to design low power mixer, so the top transistor (Switching transistor) was biased at: Vd = 1 V, Vs = 0.654 V, Vg(max) = 1.25 V (because of LO swing), Vth = 0.477 VHopefully the top transistors have sufficient Vds margin, too.
fLO = 4.9 GHz, fRF = 2.5 GHz, fIF = 2.4 GHz. Would you please tell me how to overcome the crosstalk problem? I assume that I have ideal balun and I want to check the function of mixer first.We see a lot of crosstalk, e.g. at the RF input terminals. The output signal is probably just the sum of parasitic effects. Is the design suited for 5 GHz by layout parameters?
Are you intending frequency doubling or IF mixing? In the latter case, what's the expected output frequency? Can it pass the output transformer?
I will follow this instruction.Did you operate the mixer with moderate RF and LO frequencies to verify it's function?
RFp and RFn interacts each other on the bias node.Put a large capacitor on bias net
Doesn't fit your post. In your waveforms, fLO and fRF are apparently both near 5 GHz.fLO = 4.9 GHz, fRF = 2.5 GHz, fIF = 2.4 GHz.
Doesn't make sense. Of course, DC level must be applied to the gates directly, without coupling capacitors. Trace the individual drain currents to understand how the output is generated.In fact, I changed the RF port to DC source type. I only simulate the transient with LO signal. The problem still happens.
Doesn't fit your post. In your waveforms, fLO and fRF are apparently both near 5 GHz.
Doesn't make sense. Of course, DC level must be applied to the gates directly, without coupling capacitors. Trace the individual drain currents to understand how the output is generated.
RF input signal (-50 dBm)
View attachment 132615
You see feedthrough of 2nd LO harmonic.your positive and negative RF signals DC changes during time
Might have no effect if the balun output has high common impedance (transformer winding with floating center tap).I put 10nF caps at inputs/outputs to block DC current.
Might have no effect if the balun output has high common impedance (transformer winding with floating center tap).
clock feedthrough have this much effect in the input ?
In other mixers like passive RL mixer, it effects input with 2WLo but here we have one Cgs and Cgd, it should not effect this much :/
2Wlo mixes with Wlo and if it is zero IF structure it will be filtered out.
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pleas take a screen shot from all of ur circuit not a part.
Have you ever checked there is no 2nd frequency in RF port ?? There is a beating between two frequencies ( looks like it )
Not particularly the caps. But a RF port common mode signal will be translated to an output common mode signal, just think. So my latest question was if your balun might be unsuitable by a exposing a high common output impedance and thus promoting feedthrough of the 2nd LO harmonic generated by MN0-MN3 non-linearity.Anw, the 10nF caps do not explain why IFP and IFN have same phase.
Anw, the 10nF caps do not explain why IFP and IFN have same phase.
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You can see the full schematic in reply #4 in this thread. If I misunderstand what you mean, please explain
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