CMOS I/O transceiver with 3V/5V level converter and N-tub voltage generator

An I/O transceiver with a 3-V/5-V level converter (TRCV) and an N-tub voltage generator (TUBGEN) are designed and fabricated with other CMOS standard cells on a system control chip to solve the I/O interface problem between 3-V (IC) parts and 5-V (IC) parts in the same system. This circuit is designed to support power-down mode when the 5-V power supply to periphery devices (ex., PCMCI interface device) is disconnected from a system board while the 3-V supply is active to keep the CPU in batch mode process.<>