Design on mixed-voltage I/O buffer with blocking NMOS and dynamic gate-controlled circuit for high-voltage-tolerant applications

A new mixed-voltage I/O buffer with a blocking NMOS and a dynamic gate-controlled circuit for high-voltage-tolerant applications is proposed. The new proposed I/O buffer can receive input signals with a voltage swing twice as high as the normal power supply voltage (VDD). It has been fabricated in a 0.25-μm CMOS process to receive 5-V input signals without suffering gate-oxide reliability and circuit leakage issues. The new proposed mixed-voltage I/O buffer can be easily scaled down toward 0.18-μm (or below) CMOS process to serve different mixed-voltage I/O interfaces, such as 1.8/3.3-V or 1.2/2.5-V applications.