Semiconductor device having a CMOS element as a buffer

摘要

A PMOS 21 and an NMOS 22, which are connected in series between a power supply potential Vcc and a ground potential Vss, perform ON and Off operation in accordance with data signals G1 and G2 from an output buffer control circuit 40, and generate an output signal. A Vpp generating circuit 50 generates a potential Vpp higher than the power supply potential Vcc and a back gate bias of the PMOS 21 is set at the potential Vpp. Even if a latch-up trigger current due to a surge voltage is produced, the back gate bias of the PMOS 21 is set at Vpp and therefore a potential difference caused in an N type well resistor becomes small and a base potential of a parasitic bipolar transistor disposed between the N type well 2 and a substrate 1 becomes approximate to the potential Vpp. Accordingly, the current which flows into the substrate 1 is suppressed and a latch-up tolerance is improved.