Table 1.

Oscillator-based temperature sensors in the literature.

Reference	Ring Oscillator Topology	Calibration Method	Accuracy
[11]	two ring oscillators and a subtractor	one trimming point	[−2.9 °C, 2.7 °C]
[12]	ring oscillator, biased by PTAT, sink resistor	two trimming points	±3 °C
[13]	RS register	resistor trimming, 5-bit	±1 °C
[14]	current-controlled	N/A	0.7 °C / bit
[15]	current-starved, digital control	output capacitor trimming, 4-bit	0.4 °C / bit
[16]	current-starved, digital control	N/A	0.18 °C / bit
[17]	delay line	digital comparator and time amplifier	±0.7 °C
[18]	parallel ring oscillators	zero temperature coefficient ring oscillator and voltage mapping	[−1.76 °C, 1.96 °C]
[19]	current-controlled oscillator	resistor trimming, two points	±1.5 °C
[20]	two ring oscillators, bandgap concept	two trimming points	[−1.7 °C, 2.1 °C]