The **silicon bandgap temperature sensor** is an extremely common form of temperature sensor (thermometer) used in electronic equipment. Its main advantage is that it can be included in a silicon integrated circuit at very low cost. The principle of the
sensor is that the forward voltage of a silicon diode is temperature-dependent, according to the following equation:

*V*_{BE}=*V*_{G0}(1 -*T*/*T*_{0}) +*V*_{BE0}(*T*/*T*_{0}) + (*n**K**T*/*q*)ln(*T*_{0}/*T*) + (*K**T*/*q*)ln(*I**C*/*I**C*_{0})

where

*T*= temperature in kelvins^{i}*V*_{G0}= bandgap voltage at absolute zero*V*_{BE0}= bandgap voltage at temperature T_{0}and current*IC*_{0}*K*= Boltzmann's constant*q*= charge on an electron*n*= a device-dependent constant

By comparing the bandgap voltages at two different currents, *IC*_{1} and *IC*_{2}, many of the
variables in the above equation can be eliminated, resulting in the relationship:

- Δ
*V*_{BE}= (*K**T*/*q*)ln(*I**C*_{1}/*I**C*_{2})

An electronic circuit, that measures Δ*V*_{BE} can therefore be used to calculate the temperature of the diode.
The result remains valid up to about 200 °C to 250 °C, when leakage currents become large enough to corrupt the measurement.
Above these temperatures, more exotic materials such as silicon carbide can be used instead of silicon.