Reliability of SAR ADCs and associated embedded instrument detection

Abstract

Successive-approximation-register (SAR) analog-todigital converters (ADCs) represent the majority of the ADC market from medium to high resolution ADCs. Due to its low power, high-performance and small area in Mega-Hz range, SAR ADCs are increasingly attractive for todays safe-critical applications like automotive. Recently, much research has been carried out on self-calibrations of SAR ADCs, which are mostly focussed on passive capacitor banks inside SAR ADCs. However the reliability of SAR ADCs is rarely reported, which is more related to the active circuit parts and is also essential for safe-critical applications. In this paper, the focus will be on the reliability effects and associated embedded instrument detection of a 10-bits SAR ADC in 65nm CMOS technology. The NBTI degradation in the bootstrapped switches, self-timing asynchronous SAR logics, input buffer and comparator inside a 10-bits SAR ADC are investigated as well as the overall performance degradation of the ADC. Finally, embedded instrument methods are proposed to detect these reliability influences in SAR ADCs.

Reliability assessment of 4GSP/s interleaved SAR ADC

“…Important research efforts have been made to develop robust digital circuits, with dedicated sensors to monitor reliability. In contrast, very few studies has been done to address analog circuits and especially ADCs which are integral parts of most mixed-signal circuits [1,2]. Hence, aging simulations and degradation analysis become necessary.…”

“…However, the asynchronous SAR logic and comparator can suffer from from NBTI. Some work [1] focus on the comparison of degradation in the buffer and comparator with reference to the degradation in the capacitor array and they conclude that most of the static and dynamic performance parameters are severely affected by the DAC capacitor-array degradations. Whereas, in case of the buffer and comparator degradations, only offset from the static performance parameters and all of the dynamic performance parameters are severely affected [2].…”

Ageing and Embedded Instrument Monitoring of Analogue/Mixed-signal IPs

“…All calculations are carried out in the digital domain instead of the analogue domain. After detection, simple counter actions like subtraction can eliminate the ageing effects [Wan15c].…”