layout via vs stubs
Hi,
just to make difference in two possible cases of realizing short stubs. One way is to use via at the end of the shunt line to connest to the ground. Then, short stub doesn't have any significant advantage compared to open stub - open stub has open-end capacitance that is effectively making it longer than desired, short stub has via inductance that is effectively making it shorter than desired. Via can also have resistance, so it can lower resonator Q. The only advantage of short stub is than it can provide ground return if you need one. On the other hand, if you don't need ground return, it is in my experience more advantageous to use RF short (e.g. radial stub) instead of DC short (via) at the end of the line. This can be analized very accurately either with circuit simulators or EM simulators and discrepancy due to any parasitic effect will be minimized.
flyhigh