Spread spectrum oscillators reduce EMI

Substituting AEL Crystal’s HMxxxR spread-spectrum oscillator for a conventional clock oscillator is claimed to reduce electro-magnetic interference (EMI) by at least 9dB.

The parts are a drop-in replacement for conventional clock oscillators, which are the most significant source of EMI. This means there is no need to change or add any other components such as additional filters or metal shielding, or change any of the current PCB layout. As a consequence, customers can release designs to market without time delays or any additional engineering costs.

Unlike a conventional clock, the energy of a spread spectrum clock is distributed over a wider bandwidth between two predefined frequency boundaries. The controlled modulation process can be all on one side of the nominal frequency, which is preferred if over-clocking is impractical, or 50 per cent up and 50 per cent down.