A High-Speed and Compact On-Chip CMOS Temperature Sensor for 3D-NAND Flash Memory

This paper presents temperature sensing system for 3D-NAND Flash designed for high-speed conversion speed and minimal area. The proposed temperature sensor generates temperature-independent current that produces constant slope voltage, facilitating direct temperature sensing for high-speed conversion. By using a diode-connected NMOS to track threshold voltage (VTH) variations with temperature, the area is significantly minimized. Implemented in 28nm CMOS process, the entire system achieves conversion time of 3.77µs within -40°C to 125°C temperature range and occupies active area of 3900µm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. It provides inaccuracy of -2.52°C to +1.74°C after 2-points calibration, with 0.74°C resolution. From an energy efficiency perspective, the system consumes 0.25nJ.