A low-power inverter-based CMOS level-crossing analog-to-digital converter for low-frequency biosignal sensing

Abstract

Low-power analog-to-digital conversion is a key technique for power-limited biomedical applications such as power-limited continuous glucose monitoring. However, a conventional uniform-sampling analog-to-digital converter (ADC) is not suitable for nonuniform biosignals. A level-crossing ADC (LC-ADC) is a promising candidate for low-power biosignal processing because of its event-driven properties. The LC-ADC acquires data by level-crossing sampling. When an input signal crosses the threshold level, the LC-ADC samples the signal. The conventional LC-ADC employs a power-hungry comparator. In this paper, we present a low-power inverter-based LC-ADC. By adjusting the threshold level of the inverter, it can be used as a threshold-fixed window comparator. By using the inverter as an alternative to a comparator, power consumption can be markedly reduced. As a result, the total power consumption is successfully reduced by 90% of that of previous LC-ADC. The inverter-based LC-ADC was found to be very suitable for use in power-limited biomedical devices.

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“…By using supply-sensing architecture, CMOS bioelectronics 36,[43][44][45][46][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69] can be energy autonomous. Thus, this will be beneficial for future healthcare and medical applications.…”

Darlington CMOS İnverter Tabanlı Paralel Analog-Sayısal Dönüştürücü Tasarımı

“…Karşılaştırıcı olarak kullanılan bu yapı daha sonra farklı analog sayısal dönüştürücü tiplerinde de kullanılmıştır [18,19]. Bu yapının geliştirilmesi sayesinde sadece tek başına cmos inverter devresi kullanılarak da tasarımı yapılmış paralel analog sayısal dönüştürücüler mevcuttur [15,20,21]. Bunlarda sadece inverter devresinin eşik gerilimine göre çalışan yapılardır.…”

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