Patent ID: 6121789
Filing Date: 2000-09-19
Classification: H03K

Abstract:
An output buffer comprising:a pull-down driver coupled between an output node and a ground electrode;a ramp control circuit coupled between a logical input signal and a control electrode input to the pull-down driver, wherein the ramp control has an input coupled to the output node; anda ground noise detect circuit coupled to the ground electrode, and coupled to control the ramp circuit to decrease a slew rate of a low-to-high transition of a signal applied to the control electrode input to the pull-down driver in response to ground noise above a threshold value at the ground electrode, wherein the ramp control circuit comprises:a first inverter having an input coupled to the output node;a first transistor coupled between the control electrode input of the pull-down driver and the ground electrode; anda second transistor coupled between a first gate of the first transistor and an output of the ground noise detect circuit, wherein a second gate of the second transistor is coupled to an output of the first inverter.