Capacitively Coupled Near-Threshold Biasing: Low-Power Design Based on Metal Oxide TFTs for IoT Applications

Metal Oxide Thin Film Transistors (MO TFTs) have garnered considerable interest in emerging Internet of Things (IoT) fields such as wearable electronics, displays, Radio Frequency Identification (RFID), and biomedical monitoring, owing to their flexibility and transparency. However, limitations in channel materials make MO TFT-based circuits unipolar. Unipolar circuits often exhibit elevated short-circuit power consumption, which restricts the development of MO TFTs in the IoT sector. This paper introduces a Capacitively Coupled Near-Threshold Biasing (CCNB) technique that leverages the unique Capacitance-Voltage (C-V) characteristics of MO TFTs to bias devices in the near-threshold region, achieving nearly a 95% reduction in power consumption compared to traditional designs with the device coupling ratio (channel capacitance/overlap capacitance) at 40. Furthermore, considering the significance of clock signals in IoT applications, we have also developed a low-power full-swing Ring Oscillator (RO) based on our CCNB technique, resulting in a 90% reduction in power consumption and a nearly 70% reduction in PDP compared to conventional low-power designs.