A Predictable Robust Fully Programmable Analog Gaussian Noise Source for Mixed-Signal/Digital ATE

A robust programmable analog Gaussian noise generator suitable for mixed-signal/digital ATEs is presented. Unlike conventional methods (LFSR based noise generators or resistor thermal noise amplification techniques), the user has full control of the characteristics of the Gaussian signal. Indeed, the frequency band, the mean, and variance of the distribution are fully programmable over the voltage range within the supply rails. The method consists of digitally encoding the specified Gaussian signal in a RAM, using pulse-density modulation, followed by filtering the bit stream using an analog low-pass filter. It is demonstrated that the quality of the generated noise signal is independent of the quality of the filter used; hence, making the noise source highly robust. The output of the noise generator accurately models a real Gaussian signal, even at high sigma values; thus, making it a very effective and predictable dithering signal. Two applications of the proposed Gaussian noise source are demonstrated: ADC histogram testing and high-resolution digitization