Bringing Data Converter Pairs into Chaotic Oscillation for Built-in Self-Test and Entropy Generation

Abstract

A pair comprising an analog-to-digital converter (ADC) and a digital-to-analog converter (DAC) can enter chaotic oscillation when closed in a feedback loop with a limited set of additional elements. This phenomenon can be employed for entropy generation in true random number generators (TRNGs). Additionally, the oscillation can expose defects in the components’ operation, providing an opportunity for built-in self-test (BIST). Reconfigurable loops sustaining self-oscillation characterize the oscillation-based test (OBT) approach, appealing for not requiring resources to excite the blocks under test (BUTs). While OBT has been applied to various signal processing primitives, its use in data converters has been mostly confined to specific subsystems or variations of servo-testing. Here, it is shown that chaotic OBT of data converter pairs may offer insights on their input-output characteristics, while providing entropy generation at the same time. A PIC microcontroller, together with an external DAC and some operational amplifiers, is used as a test bed to validate the approach’s scope and demonstrate its applicability to real-world systems.