large signal impedance match,help!!!

Now I use A@gilent A@DS to design Gilbert Upconversion Mixer,but because I use the design guide of A@ds,but the guide is use small signal to test the input impedance. So the LO port impedance is not accurate.

Can anyone tell me how I can test the impedance under large signal condition accurately?

Or give me some reference.Thanx very much!

My email is : carmine_rene@hotmail.com

hi
if you need any information about matching impedance network at large signal you can download this pdf .
its address is:
http://rfwireless.rell.com/pdfs/AN_721_D.pdf

I find another good article for you:
see this
http://www.sandiego.edu/~ekim/e194rfs01/zmatch.doc

If you need Pi network impedance matching you can compute your network online at this site:
http://www.raltron.com/cust/tools/ne...e_matching.asp

Find through the link bellow a reference that can solve your problem,

http://www.rfmd.com/databooks/db97/Ta0041.pdf

NandoPG

Why you need LO port input impedance of Gilbert Cell Mixer ?
Under the high level signal condition , input impedance of a Gilbert cell mixer varies by LO signal amplitude. Regarding to saturation status of bipolar transistors ( varies proportional to tanh ) input impedance will be depended on instantinous signal amplitude therefore finding a simple impedance level is almost impossible. You drive with a certain level to saturate them. That's it..

In fact LO amplitude should be high as possible high to avoid transient noise. For a simple Gilbert cell structure this level must be over 300mVpp.

But if you use more complicated device , I don't know..

In fact to drive Gilbert cell mixer , a buffer amplifier should be used to prevent LO frequency pulling..This is very important. In this case input impedance is not very important.

Regards ,

the buffer amplifier can easy match to
50ohm

hi, the first and third link is not vilad.

Can you provide a new link or uploap new file?

thank you