loaded q for pi

Hi,

For the Pi or T impedence matching network,

the two resonant L network have different Q if the

load and source impedence is different.

So, what is total Q for whole T or Pi network?

Is it the larger one?

Why?


Thanks a lot.

Best Regards.
Tony Tao

This is related to Loaded Q of the circuit, which is dependent by the individual Q’s of inductors and capacitors (XL/RS or RL/XC)
Qtotal = (Q1*Q2)/(Q1+Q2)
If Qtotal of the circuit is greater than 0.5 then, for optimum transfer of power from the source to the load, Q1 should be equal Q2. In this case, at the working frequency, the response will approach theoretically 0 dB insertion loss. If the total Q of the network is less than 0.5, there will be no peak in the response and for optimum transfer, RS should equal RL.

The total network Q = Qleft + Qright

(from the LEE book)

by the difination of q,we can use the propersion of energy saved and the energy lossed by the resistance