National Semiconductor Corporation

Weiye Lu

Elroy M Lucero

Thomas Y Tse

Wai Cheong Chan

Khusrow Kiani

In an I/O circuit, noise reduction and power savings are achieved by providing feedback from the output of the I/O driver to control the current through the pre-driver and thereby the current through the driver transistors after a non-zero time delay following a low to high or high to low data signal change.

Method and system for reducing I/O noise and power

In an I/O driver that includes a cascoded pair of PMOS driver transistors connected to a pair of cascaded NMOS driver transistors and that defines a pad output between the PMOS and NMOS driver transistors, a method of providing the CMOS I/O driver with over-voltage and back-drive protection includes providing circuitry for charging the wells of the PMOS transistors either to VDDIO during normal voltage mode by making use of the power supply, or to a common voltage during over-voltage and back-drive operation using the pad voltage.

I/O protection under over-voltage and back-drive conditions by single well charging

A quartz-crystal oscillator circuit substantially reduces the start-up time of the crystal oscillator circuit by utilizing a start-up time reduction circuit that adds additional gain to the crystal oscillator circuit during the start-up period, and removes the additional gain as the oscillator circuit nears steady state operation. Furthermore, the start-up time reduction circuit dynamically monitors the oscillation amplitude. If the build up of oscillation is interrupted, the additional gain will be re-applied.

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Weiye Lu