Effect of Q-Factor on filter performance

[WanCai]

Hi,

I understand that for inductors the higher the Q-factor the lesser the loss, but may i know for a bandpass filter, other than affecting the insertion loss what other effect does the overall Q of the bandpass filter have on the circuit.

Thank you
Wancai

 

[borich_03]

Hi,

I understand that for inductors the higher the Q-factor the lesser the loss, but may i know for a bandpass filter, other than affecting the insertion loss what other effect does the overall Q of the bandpass filter have on the circuit.

Thank you
Wancai

Look at the book "HF Filter Design and Computer Simulation",Randall W. Rhea
1994.

 

[Borber]

Effect of elements low Q is illustrated on picture. Thin yellow curves are for lossless elements filter.

 

[J0hn]

From what i understand, the higher the Q, the edge of the bandpass will be more squarish whereas for lower Q, the edge of the bandpass is very roundish. And it seem that if i increase the thickness of the substrate, the Q tends to improve.

But i like to know is that any software that is able to calculate the Q of the tranmission line? I think genesys can do it, but i can't seem to recall how issit been done? Thanks.

 

[flatulent]

Rogers Corp. has a free downloadable program called mwi.exe that can calculate losses of transmission lines. This is only the resistance and dielectric hysteresis losses. It does not calculate the radiation loss.

 

[lguancho]

Here is an example of Genesys Tline module calculation of microstrip line parameter, including unloaded Q

 

[Darren_pan]

thanks ,it's very useful~~

 

[Echo]

me too,it's very useful

 

[tronix]

As for band pass filter the width of central lobe (for amplitude to vary b/w h0/√2)
is w0/Q , so higher the value of Q sharper will be the response around w0 and hence in general better response

 

[Depp]

lerning...