How to get this expression for LC impedance?

[trashbox]

In the paper:Analysis and design of Injection locked LC dividers for quadrature generation,JSSC 2004. I can not get the expression(please see the attachment) for the impedance of LC element.

Woul you please give me any advice?
Thank you very much.

 

[sergio mariotti]

It's the expression of the Impedence wrote on Q rather than on L&C.
It's a known, general form, and it's valid regarless the resonant circuit topology.
Of course the Q expression will change as resonator topology.
Q≡Reactive Power / Dissipative Power
To find Q as function of ω, you may know L & C