Help me design and routing PCB for high frequency

[rezade]

I make quadrature demodulator for frequency 400-500MHz, I use lt5517 with quadpack 17 pin. I dont know, how wide the path pcb? what is the effect of path wide? How about the capasitif effect for adjacent line? What is the differencies between normal ground and RF ground?

 

[keith1200rs]

The PCB track width depends on your PCB material and thickness and number of layers (and where you put the ground plane). If you use 1.6mm FR4 with 2 layers you will probably find the tracks are quite wide. If you use a thinner board or 4 layers with an inner ground plane they will be narrower. There are plenty of impedance calculators on the web - e.g.

It would be worthwhile looking at the evaluation board PCB layout in the datasheet.

All the grounds should be connected to the PCB ground plane. The difference between the GNDRF and GND is that all the GNDs are internally connected - the GNDRF pins aren't.

Keith