Controlled noise generation with avalanche diodes I. Low pulse rate design

The generation of random noise with uniform avalanche diodes is investigated. A special avalanche noise diode is designed in which the pulse rate is determined by internal field emission and circuit constants, resulting in a small and predictable temperature dependence of the noise output. The spectral noise distribution is calculated for the case of a clipped sawtooth wave with small random fluctuations of the time between successive pulses. The resulting spectral distribution can, to a good approximation, be expressed as a line spectrum with overlapping harmonics. Under certain experimental conditions the harmonics overlap sufficiently that white noise is obtained over a wide frequency range, e.g. from 40 kc/s to 200 kc/s or more. The experimental results are in very good agreement with the theoretical predictions.