Design of high isolation switch in phemt MMIC

[liyi.sin]

Dear all,

I am interested in designing a hi- isolation switch. I am having problem meeting my design specification of 60 to 70 dB isolation at 1 GHz.

1)Does anyone have any paper or material that can highlighted the possible issues with this type of high isolation switch design?

2) Or Comment on how to achieved this level of isolation will be greatly appreciated.

 

[xjxmn]

Is "T" structure switch useful?

 

[liyi.sin]

What do you mean by a T structure?

 

[xjxmn]

I have thought out an ideal, you can design a switch net , two serial and at the junction you can add a switch to ground. when "on", the two switch can connect in serial. When "off", the two serial switch should turn off, and the switch to ground should be turn on. So the two side can be isolated. But I don't know whether it can get 60dB to 70dB in 1GHz. I haven't designed high frequecy circuit.

 

[liyi.sin]

I believed I am using a similar circuit. I found out the isolation is mainly due to the bond wire coupling.

Is there a good way of modelling the signal coupling? If so, how?

Or if some one out there have a better design? I would like to know about it.