Low cost rat-race mixer for x-band application
I'm designing a rat-race mixer using HSMS-8202 Schottky diode. According to application note from Avago 1136, I have started to design this mixer. I designed the rat-race hybrid coupler and the matching networks for diodes. I'm wondering if someone has already designed this mixer, because I want to know how it can be designed the low pass filter of IF section...
Thanks in advance
Raed
why not buy a X band MMIC mixer? It's vey simple.
because I want to learn the design of mixer.....please do you have any idea about design low-pass filter of this mixer?
The mixer below use a 90-deg hybrid but gives you an idea how to design the output LPF and the distributed terminations.
Thank you so much for your post....Could you please tell me how can I simulate the s-parameters of the mixer in order to calculate the input impedance of IF port?
Actually I want to design LPF and my problem is that I don't know how to calculate the impedance between the diodes.
Initially you can use a linear simulator for designing the distributed components and LPF.
After that you can use a non-linear simulator, simulating the full functioning mixer, with proper in/out impedances.
Tune the output distributed components (including LPF) for maximum IF signal, and also for minimizing the RF and LO signals (at the IF port).
Adjust the LO level for best mixer performance.
I have already designed rat-race coupler and the matching networks....but I couldn't design the LPF because I don't know how can I calculate the input impedance from diode side as shown in this figure...
So, this is the reason I mentioned to use the non-linear simulation during tuning of the LPF. In this way whatever complex impedance you get at the mixer output, you can tune the LPF properly.
Thank you so much.....I will run HB simulation for my design