input impedance of mixer in cadence

hi
thank u edaboard members for helping me a lot...

i m simulating gilbert mixer for finding its input impedance i tried it using s-parameter in cadence but the test bench i used have a balun at RF port so while measuring Z11, i think it gives input impedance at single ended input of balun but i want to measure input impedance at mixer input [balun has a input:output impedance of 50:50], & at LO input i have connected single to differential conversion network please explain me how it convert single input in to differential. Figure of test bench is attached.

If the balun is ideal ( seems to be ) the Input Impedance of the Mixer will be reflected to Single Ended Input Impedance in your simulation.

thank u BigBoss for your reply

that means if i m measuring input impedance of mixer at port using PSP in cadence & RF port is suppose port no. 1 than ZM1 will give me input impedance of circuit....is it right?

so it will give me impedance of single input of mixer other will be same because it is circuit is symetrical right?

and if have idea about LO single to differential conversion circuit please explain