advice on selecting pcb thickness for GCPW
Hello everyone,
in my company we want to enhance the bandwidth of our analog circuits to 5GHz. Up to now we have been working with 2 layer FR4 PCBs. To minimize loss and noise contribution, we want to make the step to a material like Rogers 4350B. Furthermore, we would like to use a 4 layer stack up. While gathering information on costs on different online pcb calculators, I realized that Rogers 4350B seems to be common in thicknesses of 0.254mm and 0.168mm. A costeffective solution limits the spacing/clearance to 0.1mm. In my understanding it is importand to keep the microstrip mode as low as possible in a GCPW (Grounded CoPlanar Waveguide), and by this the ratio of the slot width G to the dielectricum heigth h. This leads to a cummulation of the rf energy in the slots and by this to lower loss and noise impact. So I'm a bit confused, why common dielectrics for rf pcbs seem to be have a low heigth as bigger dielectrics should lead to better signal qualities. Do I understand something wrong? Maybe someone can give a hint which Rogers 4350 heights he is using with GCPW?
thank you in advance for every comment.