In our recent piece on board-level ESD protection, I noted that, while the board is protected during actual usage, chip-level ESD protection is focused more on what might happen to the chip during handling, before it’s inserted into its final board resting place.
Such chip-level ESD circuits are mostly standard, typically involving some kind of diode breakdown to shunt excess energy. But this is apparently a dicier deal with RF circuits, since plain vanilla ESD circuits can degrade the RF performance.
TSMC and imec recently worked on two alternatives to protect low-breakdown oxides in 60-GHz RF circuits. Both involve resonant circuits; one has two diodes, the other none – it essentially has a shunt inductor.
As reported, both circuits provide charged-device model protection with minimal disturbance to the RF specs – “minimal” meaning small enough to be considered not affected.
More info on imec’s site…