Abstract: Silicon-controlled rectifier (SCR) based circuit for ECG protection under defibrillator pulse is disclosed. The SCR-based clamp is a symmetric structure for dual-direction voltage tolerance protection based on two anti-series P-well/N-well lateral blocking junctions isolated from P-substrate by the N-buried layer. The injector regions (n+/p+) are substantially lengthened in order to accommodate a larger number of contact rows than typically used for ESD pulses specification. A stack of metal layers may also be used to provide high current and heat-sink capability with each electrode metal layer fully filled with VIAs.