Switchable MCM CMOS I/O buffers
 A switchable I/O buffer for multi-chip modules comprising a conventional I/O buffer and a miniaturized I/O buffer. A path switch selects the conventional I/O buffer or the minaturized I/O buffer according to whether the I/O interconnection is for communication off the module or chip-to-chip communication within the module. The miniaturized I/O buffer comprises a single-ended I/O buffer without electrostatic discharge protection. Two layout structures are designed for the switchable I/O buffer. A first layout structure having its path switching control provided by either a cell-programmable method or a mask-programmable method can be used for a multi-chip module or a PWB single package. A second layout structure using a pad-programmable method to provide the path switching control is suitable for a multi-chip module with flip-chip attachment technology. Four different circuit implementations of the switchable I/O buffer are presented. The switchable I/O buffer achieves higher performance with lower power dissipation in that the unnecessary heavy loading and electrostatic discharge protection are eliminated from the interconnection for chip-to-chip communication within the multi-chip module. 
Industrial Technology Research Institiute
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Jyh-Ren Ruey-Wen Chung-Tao
Yang Chien Chang