Bandgap voltage reference

If the ratio between the first and second resistor is chosen properly, the first order effects of the temperature dependency of the diode and the PTAT current will cancel out.

For this reason, in 2001, Malcovati[8] designed a circuit topology that can compensate high-order non-linearities, thus achieving an improved TD.

[9] In 2012, Andreou[10][11] has further improved the high-order non-linear compensation by using a second operational amplifier along with an additional resistor leg at the point where the two currents are summed up.

As a bandgap reference is generally based on BJT devices and resistors, the total size of circuit could be large and therefore expensive for IC design.

[a] However, the parabolic characteristic of voltage versus temperature means that a single figure in ppm/°C does not adequately describe the behavior of the circuit.

Manufacturers' data sheets show that the temperature at which the peak (or trough) of the voltage curve occurs is subject to normal sample variations in production.