Patent Number: 6,166,582

Title: Method and apparatus of an output buffer for controlling the ground bounce of a semiconductor device

Abstract: A method and apparatus of an output buffer for controlling the ground bounce and power supply noise during output switching is provided. A CMOS output buffer comprises a P-channel output transistor, a N-channel output transistor and a predrive circuit. During output pull-down transition, the predrive circuit generates a first gate voltage on the pull-down N-channel output transistor for a predetermined time, and further generates a second voltage value which is smaller than the first voltage value, then returns to the first voltage value after the elapse of the predetermined time. The predrive circuit makes the pull-down N-channel output transistor stay in the saturation region longer than the uncontrolled scheme, the steep rising gate voltage on the N-channel output transistor can be avoided with a very little speed degradation but instead of better ground bounce improvement. During output pull-up transition, the predrive circuit generates a first gate voltage on the pull-up P-channel output transistor for a predetermined time, and further generates a second voltage which is higher than the first voltage value, then returns back to the first voltage value after the elapse of the predetermined time.

Inventors: Tseng; Jiunn-Chin (Tainan, TW), Kirsch; Howard Clayton (Taoyuan, TW)

Assignee: Vanguard International Semiconductor Corporation

International Classification: H03K 19/003 (20060101); H03K 005/12 (); H03K 017/16 ()

Expiration Date: 12/26/2017