Hi, This is my first encouter with anything to do with RF design. I'm trying to design an RF PIN diode switch to meet certain specifications. I'm having considerable difficulty putting together a circuit schematic that will accomplish this. My specs are: Center frequency: 15GHz Bandwidth 3GHz Insertion loss<0.5db Isolation>25db Return loss<15db I have a seedling schematic that has values I can't modify, but I'm allowed to do really whatever I want to design the bias circuits and switching networks. I'm using ADS 2009 to do the schematic design. Attached is the seedling schematic I'm working with. Since I've never really done any design work with RF circuits, any help would be greatly appreciated. My first task to tackle, is how to achieve isolation >25db. Does anyone know how I would do this? Thanks in advance!!