A 33-ppm/°C 240-nW 40-nm CMOS Wakeup Timer Based on a Bang-Bang Digital-Intensive Frequency-Locked-Loop for IoT Applications

Abstract

This paper presents a wakeup timer in 40-nm CMOS for Internet-of-Things (IoT) applications based on a bangbang Digital-intensive Frequency-Locked Loop (DFLL). A selfbiased Σ∆ Digitally Controlled Oscillator (DCO) is locked to an RC time constant via a feedback loop consisting of a single-bit chopped comparator and a digital loop filter, thus maximizing the use of digital circuits while keeping only the RC network and the comparator as the sole analog blocks. Analysis and behavior level simulations of the DFLL have been carried out to guide the optimization of the long-term stability and frequency accuracy of the timer. High frequency accuracy and a 10× enhancement of long-term stability is achieved by the adoption of chopping to reduce the effect of comparator offset and 1/f noise and by the use of Σ∆ modulation to improve the DCO resolution. Such highly digitized architecture fully exploits the advantages of advanced CMOS processes, thus enabling operation down to 0.7 V and a small area (0.07 mm 2). The proposed timer achieves the excellent energy efficiency (0.57 pJ/cycle at 417 kHz at 0.8-V supply) over prior art while keeping excellent on-par long-term stability (Allan deviation floor <20 ppm) and temperature stability (33 ppm/ o C at 0.8-V supply).

Incremental transformation of spatial intelligence from smart systems to sensorial infrastructures

“…This also corresponds to central issues in policymaking in the design of the built environments with regard to the actors and means of urban computation and the future of new technologies (Emmitt, 2019;Zheng, 2018). The possible means of quantum computation/communication (Ding et al, 2020;Mitchell, 2003) for 'sensorial infrastructures of the future', wireless networks (Forlano, 2009), cloud computing (Zheng, 2018), and fibre-optic channels are expected to occupy the infrastructural layers. The ideals of quantum computation/communication at the city scale (Mitchell, 2003) can make it possible to talk about the actor-network theory (Latour, 2005), involving the transference between the environment and agents.…”

“…1-12), and quantum computing (Nielsen & Chuang, 2010). In this regard, even if the performance of quantum computers is not widely known/proven yet under complicated conditions, significant studies have been made, even for IoT applications (Ding et al, 2020).…”

“…Consideration of the ecological and the green via the IoT (Geng, 2017) can thus be valued as a unifying domain of personal, commercial, governmental, and institutional interests towards the transformation to the digital (Bouhai & Saleh, 2017;Kocatürk, 2017). This also envisions the challenges for cities, regarding noise, pollution, population, and traffic congestion (Zheng, 2018;Zheng et al, 2014), towards the future of robust computation with excellence in energy efficiency of 'sensorial infrastructures' (Ding et al, 2020).…”

“…Berman (2018),Davies et al (2018),Ding et al (2020),Erişen (2018),Mitchell (2003),Suzuki & Nakagaki (2013).…”

Fully-Integrated Timers for Ultra-Low-Power Internet-of-Things Nodes—Fundamentals and Design Techniques

“…Crystal oscillator is the de facto standard for the kHz-to-MHz range timer due to its excellent frequency accuracy and reliable performance [6][7][8]. Yet, the bulky off-chip crystal (e.g., 3.2×2.5 mm 2 ) contradicts the integration of compact system design, especially in Internet of Things (IoT) applications [9].…”