How is EMI emitted in a standard non-spread spectrum clock oscillator?
Non modulated oscillators generate an output signal at their intended output frequency. There is a large amount of radiated electromagnetic emission at this fundamental frequency and its harmonics. These oscillators also generate electric signals at frequencies slightly lower and higher than the intended output. These additional signals radiate electromagnetic waves over a frequency spectrum. The range of the frequency spectrum is dependent upon the mechanical and electrical design of the oscillator, power supply regulation, output termination, and printed circuit board (PCB) layout.
