Analog to digital and digital to analog conversion based on stochastic logic

Abstract

Digital to analog and analog to digital conversions can be realized in VLSI integrated circuits using a strictly digital technology and some additional analog circuits outside the IC. These techniques are based on the generation of a pulse sequence that represents a digital number. The mean value of this pulse sequence is obtained at the output of a low-pass external filter. The authors propose the use a stochastic pulse sequence instead of a traditional PWM signal. This technique has important advantages. Stochastic pulse sequences can be mathematically processed by extremely simple circuits. The product and addition of stochastic pulses can be evaluated by AND gates. The spectral properties of stochastic pulse sequences lead to less restrictive conditions to be imposed to the filter that makes the analog conversion of the pulse sequence. The authors have used this technique to implement digital to analog and analog to digital conversion in an integrated circuit that is currently being designed for a Spanish company.