Coding for Delta I Reduction
Original Publication Date: 1988-Apr-01
Included in the Prior Art Database: 2005-Feb-15
Coded data on bus interconnections between logic chips or logic boards can undergo large net current flow changes, referred to as delta-I, during switching from one signal to another. A coding system for delta-I reduction changes an N bit word to an N+2 bit code of which K bits are always on, and to reduce coding complexity, at least some of the bits of the N bit word remain intact as part of the N+2 bit code. (Image Omitted) A further feature is that, in reconstructing the original data word, the intact bits from the original word are not needed. An example of the system is given for a four-bit data word, ABCD, which is converted to a code word ABWXYZ in which three bits are always on. When signals leave and enter a chip switch state, changes in current (delta-I) can be substantial.