Hi, all,

I met a strange problem. When I did the simulation for the passive mixer, I apply a LO square signal to the switches of the mixer, it works fine, two of the switches are in linear region and others are off. But when I apply a sinsoid signal , it didn't work, all the switches are off. Has anybody met this problem before? Any idea would be appreciated.

Thank you very much.
James

Hi, aaron_do,

I have tried both way:

1. No bias for the passive mixer, I use ideal LO square, 600mVpp, it's working, but when I changed to LO sinusoid with the same amplitude , it didn't work.

2. If I have a 300mV bias to the gate of all the switches, applying a 300mVpp LO square,  it's still working. but when I changed to LO sinusoid with the same amplitude, it didn't work.

It's quite wiried I think, is it possible that maybe some settings in the spectreRF or some properties of model will affect this ?

HI,

Let's say we have a 300mV dc  bias applied to all the gate of the switches, and sinusoid LO+ amplitude is 300mVpk to one of the pair, and LO- has 300mVpk to the other pair. Then the dc simulation is run.

I check the dc operating point, all the switches have the Vgs = 300mV, Vds = 0, Vth= 569mV, actuall, the amplitude of sinusoid didn't add to the gate voltage. The 'region' is 0, this is also very strange, at least it should be region 3(weak inversion) I think.