Low electromagnetic interference clock oscillator module

A low noise clock oscillator module for plugging into a standard DIP clock oscillator socket of a motherboard to replace the clock oscillator chip that normally plugs into said DIP clock oscillator socket, comprising:

• a printed circuit substrate separate from said motherboard and having a ground plane;
• clock generator means mounted on said substrate for generating spread spectrum clock signals from reference clock signals said clock generator means having an analog ground output coupled to analog circuitry therein and a digital ground output coupled to digital circuitry therein;
• and wherein said printed circuit substrate has separate digital and analog ground plane traces thereon, said analog ground plane being connected to said analog ground output and said digital ground plane connected to said digital ground output, and wherein said printed circuit substrate has a plurality of electrical connection pins having a physical configuration and layout and electrical coupling between said clock generator means and said pins such that said clock oscillator module can be substituted for a conventional clock oscillator chip by plugging said clock oscillator module directly into the same standard DIP integrated circuit socket into which said clock oscillator chip was formerly plugged, and wherein said analog and digital ground planes are electrically connected together at the location of a ground pin which makes an electrical connection to a ground bus of said motherboard through said standard DIP integrated circuit socket.

A low noise clock oscillator module for plugging into a standard DIP clock oscillator socket of a motherboard, comprising:

• a printed circuit substrate separate from said motherboard and having a ground plane;
• clock generator means mounted on said substrate for generating spread spectrum clock signals from reference clock signals;
• first connection means for providing a single point electrical connection between said ground plane on said printed circuit substrate and a ground conductive trace on said motherboard and for coupling said ground plane to said clock generator means;
• second connection means for providing electrical connection between a power source on said motherboard and said clock generator means and for providing electrical connection of spread spectrum clock signals generated by said clock generator means and a clock bus on said motherboard;
• and further comprising:
• switch means for controlling the amount of spread spectrum modulation performed by said clock generator means on said reference clock signals in steps, and for controlling the input frequency range for said reference clock signals in discrete ranges and for controlling the amount of frequency multiplication of said clock reference signals;
• and further comprising a plurality of EMC filters mounted on said printed circuit substrate that couple each of said power source, said ground conductive trace and said clock bus of said motherboard to said clock generator means.