Iref

Iref is a term used in electronics to denote a reference current—a stable, well-defined current used to bias circuits and set operating points. In analog and mixed-signal design, an Iref source provides a predictable current to multiple circuit blocks, helping ensure consistent performance across temperature, supply voltage, and manufacturing variations.

Common implementations include bandgap-based current references, which exploit the predictable temperature behavior of a proportional-to-absolute-temperature (PTAT) voltage combined with a CTAT component to cancel drift, producing a reference current that is relatively insensitive to temperature. Other approaches use MOS or bipolar current mirrors, sometimes in a cascode configuration, to generate a fixed current from a supply, with trimming or calibration to improve accuracy. Subthreshold MOS current sources employ the transistor saturation region to produce low-current references with favorable power characteristics, though they can be more sensitive to process variations.

Iref is widely used to bias operational amplifiers, comparators, analog-to-digital and digital-to-analog converters, voltage regulators, and other bias networks within integrated circuits. In precision applications, designers specify the nominal Iref and its allowable drift, balance between power dissipation and accuracy, and account for temperature coefficients and process corners.

While the general concept is simple, practical Iref designs require careful layout, supply and thermal considerations, and sometimes calibration to achieve the desired stability. See also current source, current reference, bandgap reference, and current mirror.