Digital asynchronous on-chip temperature measurement using a buffer ring

Digital on-chip temperature measurement techniques usually require either a highly accurate clock frequency, or additional analog-to-digital conversion circuitry. This study proposes and investigates the applicability of a buffer ring for on-chip temperature measurement. The described concept provides a digital representation of temperature, yet it doesn't require a clock signal or ADC. Therefore it can be applied in purely analog or asynchronous ICs, where it's rather easy to implement. Simulations show accuracies averaging around one kelvin over a range of at least -25°C to 85°C.