Precision Voltage References for Low-Power Systems
Keywords:
voltage reference, temperature sensor, low power, curvature compensation, CMOSAbstract
This work presents a comprehensive design methodology for precision voltage references tailored to low-power, area-constrained systems. The central challenge addressed is achieving high accuracy and low temperature drift without relying on costly backend nonlinearity correction or large passive components. Two complementary design directions are explored. The first focuses on a compact temperature sensor that attains a three-sigma inaccuracy of plus or minus zero.25 degrees Celsius over the automotive temperature range from minus 40 to 125 degrees Celsius, occupying only 0.0251 square millimeters. The second direction realizes a 2.1 microampere bandgap reference operating from 1.65 to 5 volts with a temperature coefficient of 10 parts per million per degree Celsius, enabled by source-degenerated piecewise curvature compensation. A mixed-signal architecture is proposed, combining a substrate PNP sensing element with chopper stabilization and dynamic element matching to suppress offset and low-frequency noise. The piecewise curvature correction is implemented through a segmented current mirror that injects complementary temperature-dependent currents into the summing node. Fabricated in a standard 180-nanometer CMOS process, the prototypes demonstrate robust performance across supply and temperature variations. Measurement results show that the sensor achieves its target accuracy without any digital trimming or backend calibration, while the reference maintains regulation under supply fluctuations as low as 1.65 volts. The combined system consumes less than 3.5 microamperes from a 1.8-volt supply, making it suitable for battery-powered Internet of Things nodes and implantable medical devices. Statistical analysis over multiple samples confirms the reliability of the proposed techniques. The results indicate that careful analog design can eliminate the need for power-hungry digital correction, thereby reducing system cost and complexity. This paper provides detailed circuit implementations, layout considerations, and extensive experimental validation, offering a practical blueprint for engineers seeking to integrate precision references into energy-harvesting and edge-computing platforms.References
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