Switching Noise Reduction Using Combinatorial and Sequential Logic
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
Switching noise is defined as being the resultant of large changes of current in off-chip drivers and terminators reflecting through the inductance of power distribution nets to affect the "state" of "quiet" drivers. The amount of noise generated at any given instant depends upon the number and type of circuits switching at or close to that instant. In an effort to reduce (at the expense of logic) the large changes in current, this disclosure attempts to identify a method so that these changes in current can be identified and avoided. Functions of Elements: Hold Reg An n bit register that will contain the previous cycle's value in the "register". Bit By Bit This logic performs a bit by bit "exclusive XOR OR" on the hold register and the system register to determine which bits are switching.