12-bit Delta-Sigma ADC operating at a temperature of up to 250C in Standard 0.18 $mu$m SOI CMOS

2024-12-31

AI Summary

To address the critical need for high-temperature analog-to-digital conversion in harsh environments such as oil/gas extraction and aerospace, this work presents a 12-bit discrete-time delta-sigma ADC operable up to 250°C—surpassing the conventional automotive-grade CMOS temperature limit of 175°C. The design introduces three key innovations: leakage-compensated dummy transistors to mitigate temperature-induced leakage current, clock-boosting techniques to suppress supply/substrate coupling, and a high-temperature-robust architectural optimization strategy. Implemented in XFAB XT018 0.18-μm SOI CMOS technology, the prototype achieves, at 250°C, an SNR of 93.2 dB, an ENOB of 12 bits, a power consumption of 44 mW, and a core area of 0.065 mm², yielding a Schreier figure-of-merit (FOM) of 140 dB. Crucially, the high-temperature overhead is only 13.7%, demonstrating substantial improvements in both thermal reliability and energy efficiency.

Technology Category

• Machine Learning: Hardware-aware ML
• Application Domains: Internet of Things, Sensor Networks & Smart Cities
• Search and Optimization: Sampling/Simulation-based Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines
• Graph Algorithms and Modeling for the Web: Algorithms and analysis for heterogeneous, signed, attributed, multi-relational, temporal, higher-order, and annotated Web-related graphs

Abstract

Some applications require electronic systems to operate at extremely high temperature. Extending the operating temperature range of automotive-grade CMOS processes -- through the use of dedicated design techniques -- can provide an important cost-effective advantage. We present a second-order discrete-time delta-sigma analog-to-digital converter operating at a temperature of up to 250 $^circ$C, well beyond the 175 $^circ$C qualification temperature of the automotive-grade CMOS process used for its fabrication (XFAB XT018). The analog-to-digital converter incorporates design techniques that are effective in mitigating the adverse effects of the high temperature, such as increased leakage currents and electromigration. We use configurations of dummy transistors for leakage compensation, clock-boosting methods to limit pass-gate cross-talk, and we optimized the circuit architecture to ensure stability and accuracy at high temperature. Comprehensive measurements demonstrate that the analog-to-digital converter achieves a signal-to-noise ratio exceeding 93 dB at 250 $^circ$C, with an effective number of bits of 12, and a power consumption of only 44~mW. The die area of the converter is only 0.065~mm$^2$ and the area overhead of the high-temperature mitigation circuits is only 13.7%. The Schreier Figure of Merit is 140~dB at the maximum temperature of 250 $^circ$C, proving the potential of the circuit for reliable operation in challenging applications such as gas and oil extraction and aeronautics.

Problem

• High Temperature
• Delta-Sigma Converter
• 12-bit

Innovation

• High-temperature tolerance
• Delta-Sigma Converter
• Extreme environment application