Lets say I have an inductor, L1 = 22 nH, with a quality factor (Q) of 50. I need an inductor of 44 nH, so I put two L1s in series. Will the Q of "the combined inductor" be 50?

What if I want half the inductance, and place two L1s in parallel?

Best regards -paw


The value of Q relates the impedance of the inductor to its resistance:

Q = X(L)/R, so for a frequency f,

Q = 2 pi f L / R.

For a series connection both L and R sum, so

Q' = 2 pi f (2L) / 2R

The factors of 2 cancel, and the Q of the composite inductor (Q') is identical to the Q of the component inductors (for the case identical Qs).

The same calculation can be made for any number of inductors, in series or in parallel. In all cases, the composite Q will lie somewhere between the highest and lowest Qs of the individual components.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.