ESD protection with uniform substrate bias

摘要

Protection circuitry (100) for protecting an integrated circuit against an ESD pulse is provided. The protection circuitry (100) includes a discharge circuitry (101) on a substrate (106) that discharges an ESD pulse to the integrated circuit to ground (104a). The protection circuitry (100) also includes a drive circuitry (102) that uses a portion of the ESD pulse voltage to bias the substrate (106) using a first guard ring (110) in the substrate (106), which surrounds the discharge circuitry (101) and drive circuitry (102). The protection circuitry (100) further includes a second guard ring (120) in substrate (106), which surrounds the first guard ring (110) and connects to Vss/ground potential (104c), thereby providing uniformity of the substrate bias.