Design of 2xVDD-tolerant mixed-voltage I/O buffer against gate-oxide reliability and hot-carrier degradation

A new 2xVDD-tolerant mixed-voltage I/O buffer circuit, realized with only 1xVDD devices in deep-submicron CMOS technology, to prevent transistors against gate-oxide reliability and hot-carrier degradation is proposed. The new proposed 2xVDD-tolerant I/O buffer has been designed and fabricated in a 0.13-μm CMOS process with only 1.2-V devices to serve a 2.5-V/1.2-V mixed-voltage interface, without using the additional thick gate-oxide (2.5-V) devices. This 2xVDD-tolerant I/O buffer has been successfully confirmed by simulation and experimental results with operating speed up to 133 MHz for PCI-X compatible applications.