1. Field of the Invention
The present invention relates to a buffer, especially for an integrated circuit pad.
2. Discussion of the Related Art
An output pad of an integrated circuit is conventionally connected to a high supply potential by a P-channel MOS transistor and to a low supply potential by an N-channel MOS transistor. Both transistors are generally controlled in phase opposition without overlapping, that is, each of the transistors is turned on only if the other is effectively off. A high current surge which would occur during a time interval where both transistors are on at the same time is thus avoided.
Technologies become faster and faster, so that the signal switching edges on output pads becomes steeper and steeper.
In some applications, high frequency logic signals are desirable and these signals have steep edges.
However, in some other applications, for example, in a television set, the logic signals external to the integrated circuit have a low frequency with respect to the maximum operating frequency of the integrated circuit, and these signals have extremely steep edges which generate wide spectrum electromagnetic radiation. Such electromagnetic radiation may disturb the operation of surrounding circuits. There are even standards for limiting electromagnetic radiation emission.
It is thus desired to reduce the electromagnetic radiation emission of integrated circuits providing logic signals of relatively low frequency.