2xVDD-tolerant crystal oscillator circuit realized with 1xVDD CMOS devices without gate-oxide reliability issue

A new 2xVDD-tolerant crystal oscillator circuit realized with 1xVDD CMOS devices without suffering gate-oxide reliability issue is proposed, which is one of the key mixed-voltage I/O cells in a cell library. The proposed circuit is realized with only thin gate-oxide devices with floating n-well technique. The proposed 2xVDD-tolerant crystal oscillator circuit has been designed and verified in a 90-nm 1-V CMOS process to serve 1/2-V mixed-voltage interface applications.