Abstract: A driver circuit for limiting electrical noise on a quiescent signal is provided which includes a Transition High Driver circuit, a Transition Low Driver circuit, a Quiescent High Driver circuit, and a Quiescent Low Driver circuit. The driver circuit comprises means for driving an electrical signal with a presumed noisy Transition Power Supply network while it is transitioning from a low voltage level to a high voltage level or vice versa. The signal is driven by the Transition Power Supply network until the electrical signal reaches its quiescent voltage level. At this time, the signal is no longer driven by the Transition Power Supply network but rather by a presumed clean Quiescent Power Supply network. In this manner, noise from transitioning signals is prevented from coupling onto quiescent signals.

Abstract: A staged CMOS output buffer has multiple output transistors connected in parallel and driven by corresponding predrivers. Each predriver has a first input from which an inactive output transistor can be turned on, and a second input from which the other, active output transistor can be turned off. The input to the output buffer is coupled directly to the second input of both predrivers to turn the output transistors off when switching begins, and a resistor-capacitor (RC) circuit is inserted between the first inputs to stagger the predriver turn-on times to reduce the peak and slope of the switching current. The predriver employs chains of pass transistors to achieve both tri-state functionality and the simultaneous turn-off necessary for the staged configuration. A split termination is also employed to reduce switching current, especially NMOS-PMOS crossover current.