Low-Capacitance and Fast Turn-on SCR for RF ESD Protection

With the smaller layout area and parasitic capacitance under the same electrostatic discharge (ESD) robustness, silicon-controlled rectifier (SCR) has been used as an effective on-chip ESD protection device in radio-frequency (RF) IC. In this paper, SCR's with the waffle layout structures are studied to minimize the parasitic capacitance and the variation of the parasitic capacitance within ultra-wide band (UWB) frequencies. With the reduced parasitic capacitance and capacitance variation, the degradation on UWB RF circuit performance can be minimized. Besides, the fast turn-on design on the low-capacitance SCR without increasing the I/O loading capacitance is investigated and applied to an UWB RF power amplifier (PA). The PA co-designed with SCR in the waffle layout structure has been fabricated. Before ESD stress, the RF performances of the ESDprotected PA are as well as that of the unprotected PA. After ESD stress, the unprotected PA is seriously degraded, whereas the ESD-protected PA still keeps the performances well. key words: electrostatic discharge (ESD), low capacitance (low-C), power amplifier (PA), radio-frequency (RF), silicon-controlled rectifier (SCR), waffle layout