Help to design a 1GHz to 2GHz BPF using FR4 in ADS software
Any one know how to design.. i already simulate alot of pattern using ridge and stub . but can't get the desired result.
FR4 = bad for filters! Anisotropic, poor er control, which you need to make a bandpass filter. So UNLESS you are using only lumped elements soldered onto the board, use another type of board. FR4 would make poor, uncontrolled, transmission line resonators!
You can design this filter with a cascaded LC low pass and LC high pass. You can use FR4 as the PCB, but you cam also use any other low loss PCB, such as Rogers PCB.
You can use HPF+LPF structure. For example HFCN-800 and LFCN-2150 Minicircuits. This filter will be smaller than any other.
I think the better solution is a microstrip combline filter, but anyway FR4 is bad for filtering...
FR4 is not the best way to go but it will work (sort of).
There are various boards out there like RT Duroid / Arlon but they can be expensive
and difficult to work with for various reasons.
You don't say what you are using this filter for. So it is a little difficult to
give advice.
As a rough rule of thumb if the bandwidth is greater than +-12% of the center
frequency you are better off designing a low pass followed by a high pass.
You do however need to seriously consider termination as connecting any type
of filter to a double balanced mixer for instance effects the mixers performance.
I also agree! FR4 is not the best way !
FR4 is perfectly fine IF all the reactive components of the filter are lumped elements.
If the transmission line lenghts and widths are used as filtering elements, then FR4 is a poor choice of substrates.
Just when you think you know an answer...you find something new! Here is a guy using FR4 up to 6 Ghz:
Make a quick-turnaround PCB for RF parts - 2010-12-15 11:00:00 | EDN
I do not agree with that. FR4 is a lossy dielectric, so avoid building distributed capacitive elements. However, using metal traces as inductors works just fine on FR-4.