Controlled noise generation with avalanche diodes II. High pulse rate design

Abstract

The low pulse rate design of an avalanche noise diode described by Haitz¹is modified in order to obtain a Gaussian probability distribution. The essential modification is an increase of the avalanche pulse rate from less than 10⁴sec^-1to more than 10⁶sec^-1. This high pulse rate is achieved, in a controlled way, by reducing the breakdown voltage from about 30 volts to 12 volts. As with the low pulse rate design of Haitz [1], the avalanche pulse rate is determined by trigger carriers generated by internal field emission. Spectral voltage density and temperature coefficient are estimated and found to be in good agreement with the experimental results of 0.5 mV per c/s^1/2and -8.10^-3/°C, respectively. The spectral voltage density is fiat within ±1 dB over the frequency range from 10 c/s to 200 kc/s. After passing the noise through a low pass filter with a cutoff frequency of 200 kc/s the probability distribution of the noise voltage is Gaussian. The spectral voltage density is practically insensitive to variations of the supply voltage between 15 volts and 25 volts, corresponding to a current variation from 30 µA to 130 µA.