Abstract: A circuit for generating a digital noise signal characterized by an evenly distributed frequency content for a particular frequency bandwidth of the digital noise signal includes a word signal generator for generating a random sequence of N-bit digital word signals with each cycle of a system clock signal provided to the word signal generator, where N is a non-zero integer. The noise generating circuit further includes a shaping circuit which transforms the random sequence into a shaped sequence of N-bit digital word signals, and a frequency synthesizer which is responsive to the shaped sequence and which generates the digital noise signal.

Abstract: A protection circuit for use with an electromagnetic interference filter used in conjunction with a three phase power circuit operating at a particular line frequency includes three capacitors which are coupled to the output terminals of the electromagnetic interference filter. The electromagnetic interference filter and the power circuit have a resonant frequency which is substantially equal to the line frequency. The capacitors of the protection circuit have values which are selected to change the resonant frequency of the electromagnetic interference filter and power circuit such that the resonant frequency is not substantially equal to the line frequency. A protection circuit assembly for use with an electromagnetic interference filter includes a base plate, three ceramic capacitors, three heat conducting substrates, and a protective cover which is mounted on the base plate. The capacitors are mounted on the heat conducting substrates, and the substrates are mounted on the base plate.