A 7.4μJ.ppm2 Resistance Sensor with ±120ppm (3σ) 1-Point-Trimmed Inaccuracy and <4ppm/°C Temperature Drift from -55°C to 125°C

Resistance sensors are widely used for acquiring environmental parameters, such as temperature [1], [2], chemical [3], and pressure [4]. To suit the needs of high-end Internet of Things (loT) applications, such sensors should be both energy-and cost-efficient but not at the expense of their accuracy and stability over PVT. Traditionally, such sensors are referenced to high-accuracy low-drift off-chip resistors [3, 5], which are bulky and expensive. For those referenced to onchip resistors [1, 6], their accuracy is limited by process variations, while their temperature stability is limited to tens of $\mathrm{ppm} /{}^{\circ} \mathrm{C}$. Alternatively, resistance can be converted to frequency via a capacitive reference [2]. However, [2] is designed for sensing on-chip thermistors, and its overall performance, especially area and inaccuracy, is still limited by the readout electronics.