| 摘要 |
A controlled-slope output buffer is furnished to reduce electro-magnetic interference (EMI) and ground bounce noise which commonly arises in output buffers in a VLSI chip. In the controlled-slope buffer, output current pulses are shaped to reduce higher frequency signal components. Corrective shaping of the electrical signals by the controlled-slope buffer is effective in reducing EMI emissions in a frequency range from 200 to 1000 MHz. Output signals of the controlled-slope output buffer have voltage slopes which are substantially the same as output signals generated by conventional output buffers. However, the controlled-slope output buffer generates output signals in which the shape of the current pulse is greatly improved for reducing EMI and ground bounce noise. In the controlled-slope buffers according to the present invention, current pulses have a triangular shape when they are drawn in the time domain. This shape of current pulse results in the lowest achievable time derivative for a given capacitive load. Current pulses having this shape also reduce ground bounce levels in an integrated circuit chip.
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