Jing
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Hello, I am an university student. I use Cadence to analyze the LO leakage of direct conversion Gilbert cell mixer. It is well known that LO selfmixing is quite serious, sometimes the DC offset can saturate the following circuit. However, my simulations show me that LO feedthrough is not serious at all, when LO = -10dBm, LO feedthrough at RF port = -110dBm. I feel quite strange. Some papers often said their mixers have LO leakage around -40dB or -50dB. I have used two methods to obtain the LO leakage. One is PSS+ PXF to get the LO signal gain at the RF port with RF source as DC, the other is only PSS analysis to get the RF port signal at those harmonics of fundermental frequency, therefore the signal power at LO frequency is obtained. Both of the two methods give me very low LO leakage. I wonder whether the methods are right or wrong. I am looking for a CMOS Gilbert cell mixer circuit with poor isolation, high LO feedthrough. If somebody has, wound you be so kind to share it to me? Please send it to my Email box " patrick_hot@163.com ", thanks a lot.
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