Bidirectional ESD Protection Device Using PNP With pMOS-Controlled Nwell Bias

We demonstrate a PNP-based bidirectional ESD protection device with base bias controlled by two pMOS transistors, realized in a 0.18-μm CMOS process for 5-7 V applications. With respect to the conventional floating-base PNP device, very similar ESD performance is achieved. Due to the presence of extra parasitic diodes, the dc breakdown (V
_BD
) and holding (V
_H
) voltages are extended up to 8.0 and 7.6 V at 150 °C, respectively. Only a very limited area increase is needed and no extra mask is required for this implementation.