How to select the Q of L and C
Can anybody tell me how to select the Quality factor of Inductors and Capacitors?
My operating frequency is 2.45GHz. Because the component manufacturer gives some 'Q'values which they have measured upto some frequency ranges only.(may not be upto our required frequency).
My doubt is whether we have to calculate(for required frequency) using wL/R or is there any other way to get that from the vendor datasheet?
if we have to calculate, how to compare the calculated values with values in component datasheet?
Please suggest me how to proceed on this issue...
Usually the passive component manufacturers measure the Q factor at low frequency (approximately 100MHz) and use interpolation to get the value for higher frequencies.
There are a few modes of interpolation:
-Q varies with frequency, resistive losses constant (the most used)
-Q varies as SQRT with frequency
-Q remains constant over frequency, resistive losses track the reactance X(L or C)
There is the Q of the component and the Q of the circuit (or Loaded Q).
Component Q does have an effect on circuit Q, but the reverse is not valid.
The loaded Q of the circuit depends by:
-The source resistance (Rs)
-The load resistance (RL)
-The Q of the component
Mr Vodafone,
thank you very much for the reply.
Hello Mr Vodafone,
In all simulators if you select a Practical L and C instead of Ideal L and C , we have to enter the 'Q' of the components and the frequency at which the Q was measured, ofcourse the values of L and C also.
In that case shall we enter whatever the values given in the datasheet ?( what ever our operating frequency may be) or we need to do the interpolation which you told in previous reply?
The interpolation is done automatically by the simulator.
Just put the value from the datasheet and specify the frequency on the simulator.
Mr Vfone, thanks a lot.