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It is only a capacitor to tune the resonator.
Inductor is not shown and is done using bondwires. As there is usually a certain level of inaccuracy in the bondings inductance, designers add this multifinger cap to adjust the resonant frequency (it requires new top mask to adjust it).
But on silicon substrates fringe capacitors are rarely used because of very low capacitance values.In this photo, with this fringe capacitor ( depending of course on tech. ) will show very small amount of capacitance value..around few fF maybe less. With this value, any bonding inductance can not be in a resonating witha reasonable frequency.
I think it's a ESD protection diode.. not a fringe cap. nor square spiral inductor..If the photo was coloured, we can say more precisely..
It looks a little bit strange..
usually this structure is used in advance of classical varactor tuning+ cap banks for VCO sub-bands.
Imagine you need to go to a fast production run and you have an high freq VCO (5 GHz).
With 1 nH inductor, just as an example, and a total switched cap bank of 1 pF, you got the correct freq.
How to deal with inaccuracy of bonding/unaccounted parasitics?
Adding such a module (for example 50 fF total), you can adjust in a couple of weeks (only last metal of a properly stopped process) 2.5% the VCO freq.
Don't tell YOUR Big Boss who gave you this hint... (joking of course).
Walkingsun, could you please attach the complete IEEE paper?