5.8 A 4.7nW 13.8ppm/°C self-biased wakeup timer using a switched-resistor scheme

Miniaturized computing platforms typically operate under restricted battery capacity due to their size [1]. Due to low duty cycles in many sensing applications, sleep-mode power can dominate the total energy budget. Wakeup timers are a key always-on component in such sleep modes and must therefore be designed with aggressive power consumption targets (e.g., <10nW). Also, accurate timing generation is critical for peer-to-peer communication between sensor platforms [1]. Although a 32kHz crystal oscillator can provide low power [2] and accurate long-term stability, the requirement of an off-chip component complicates system integration for small wireless sensor nodes (WSNs).