Inductor Q factor calculation from SPICE AC analysis (2023 Update)

Could some electronics guru here please clarify this ? S{OCE AC analysis allows measurement of small signal s parameters. Using these measured values, the elements of the impedance matrix(Z matrix - Z11, Z12, Z21 and Z22) cam be calculated(messy but straightforward calculation, done easily with C code) Once the elements of the Z matrix have been calculated, the input, output impedances of the 2 port network can be calculated(as before messy but straightforward calculation, easily done with C code). For an inductor operating at RF|microwave frequencies in the non-resonace frequency range, the quality factor is (wL/R(f)) w -> angular frequency, L inductance(geometry based) and R(f) the frequency dependent resistance. So, if one were to measure the Q factor of a microstrip rectangular inductor e.g., at 759 MHz, which of Z11, Z12, Z21 , Z22 Zin, Zout would be used to get the Q factor? All hints|suggestions will be greatly appreciated. Thanks in advance.

Reply to
amal banerjee
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There are several definitions of Q, which are all pretty much equivalent in the high-Q limit but differ widely when Q <= 2-ish.

omega_0 L/R ~ 1/(omega_0 R C) ~ 1/(logarithmic decrement per cycle), etc.

Cheers

Phil Hobbs

Reply to
Phil Hobbs

Actually, the definition of the Q factor Q = wL/R(f) keads to an straightforward solution, given that impefance Z = R + j wL and L is geometry dependent. So the test setup in SPICE consists of a signal source connected in series to the test inductor and other end of the inductor is grounded. Then, for each each frequency (in the range to be considered) measure the voltage across the test onductor, and the current through it. Then |Z| = V/I. Using Z = R + j wL, and the measured value of |Z| at the test frequency, and calculated R(f), get wL and then Q.

Reply to
amal banerjee

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Reply to
Anthony William Sloman

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Reply to
Edward Hernandez

The John Doe troll stated the following in message-id <sdhn7c$pkp$ snipped-for-privacy@dont-email.me:

And the John Doe troll stated the following in message-id <sg3kr7$qt5$ snipped-for-privacy@dont-email.me:

And yet, the clueless John Doe troll has itself posted yet another incorrectly formatted USENET posting on Sun, 31 Oct 2021 08:50:06 -0000 (UTC) in message-id <slllbu$8nh$ snipped-for-privacy@dont-email.me.

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Reply to
Edward Hernandez

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