Vertailujännitelähde

A vertailujännitelähde, or voltage reference, is an electronic circuit that produces a stable, constant output voltage that is largely independent of changes in the input voltage, load current, and temperature. This stable voltage serves as a reliable reference point for other electronic circuits, particularly for analog-to-digital converters (ADCs), digital-to-analog converters (DACs), and power management systems.

The core function of a voltage reference is to provide a precise and unchanging voltage. This is crucial in applications where accuracy is paramount. For instance, in an ADC, the output digital code is directly proportional to the input analog voltage relative to the reference voltage. A drift in the reference voltage would lead to inaccurate digital readings. Similarly, in a DAC, the output analog voltage is determined by a digital code and the reference voltage.

Various technologies are employed to create voltage references, including Zener diodes, bandgap references, and buried Zener diodes. Zener diodes rely on the Zener breakdown phenomenon to establish a relatively stable voltage. Bandgap references utilize the predictable voltage-temperature characteristics of semiconductor junctions to achieve a low temperature coefficient. Buried Zener diodes offer improved stability and noise performance compared to standard Zener diodes.

The performance of a voltage reference is typically characterized by its accuracy, temperature stability (temperature coefficient), long-term stability, and noise. Designers choose a voltage reference based on the specific requirements of their application, balancing factors like cost, power consumption, and required precision.