Ultra-Low-Overhead Arbitrary-Waveform Generation as a Circuit Macro: Augmenting the Characterization of Radiation-Induced Transient Effects in Highly Scaled Integrated Circuits

Abstract

Arbitrary waveform generators (AWGs) are not typically feasible as subsystems on integrated circuits due to their size and complexity, but they are versatile circuits that are broadly useful. The purpose of this work is to show that by prioritizing minimal overhead and designing for targeted performance, as necessary for the application, it is possible to create a reusable on-chip AWG circuit macro in a small form factor. To support this claim, details and results are provided for a proof-of-concept implementation in a 45nm partially depleted silicon-on-insulator process. The presented design is able to achieve a small size by eliminating the complicated calibration and filtering circuitry commonly used in contemporary designs, instead relying on intrinsic accuracy of the base circuits. The reliability and accuracy of the AWG are driven by careful design down to the layout level, including the development of a variant of the traditional common-centroid layout technique called distributed-centroid layouts (DCL), which addresses the importance of bias circuitry in mitigating process-induced mismatch. A custom simulation workflow was developed to investigate the effectiveness of this technique at the circuit level as compared to other designs from the literature. The proof-of-concept circuit was designed to improve the characterization of radiation-induced transient effects in highly scaled integrated circuits by providing built-in self-test and hardware-emulation capabilities to a custom photocurrent measurement circuit (PMC). Details of this specific application are explored in detail, along with experimental measurements made using flash x-ray and pulsed laser sources. Alternative AWG designs that might benefit a broader application space beyond radiation effects are also provided.