Measurement of Temperature Effect on Comparator Offset Voltage Variation

Comparator offset voltage often limits the perfor-mance of a system. This paper demonstrates a measurement circuit of offset voltage variation. The digital nature of the circuit allows complete automation to enable high-volume measurement. We evaluate the temperature effect on offset voltage for 255 near-minimum size comparators fabricated in a commercial 65 nm general-purpose process. Detailed evaluation of offset voltage under a wide temperature range reveals that the temperature drift coefficient of offset voltage is a few mVs over 100
^o
C. We also reveal that asymmetric sizing will cause large drifts in offset voltage, in the order of several tens of mV over 100
^o
C. Thus, offset calibration circuits as well as circuits utilizing offset voltage variation need to take sufficient measures.