A CMOS Temperature-to-Digital Converter with an Inaccuracy of ± 0.5° C (3/spl sigma)from -55 to 125°C

This paper describes a CMOS temperature-to-digital converter (TDC) based on thermal diffusivity sensing, which is an interesting alternative to conventional band-gap temperature sensors because the thermal diffusivity of bulk silicon is insensitive to process spread. Compared to previous work of Makinwa, K.A.A., et al, (2006), this converter does not require off-chip analog components, operates over a wider temperature range and has a digital output. Furthermore, its output is a much more linear function of temperature. The TDC has an untrimmed device-to-device spread of ±0.5°C (3σ) over the military temperature range (-55 to 125°C).