^ For example, 1♚ cathode current with the Maxim Integrated MAX6009 shunt voltage reference.

^ For example, LT6657 from Linear Technology and ADR4550 from Analog Devices.

1984, US Patent 4447784, Temperature compensated bandgap voltage reference circuit, Robert Dobkin.

1981, US Patent 4249122, Temperature compensated bandgap IC voltage references, Robert Widlar.

1971, US Patent 3617859, Electrical regulator apparatus including a zero temperature coefficient voltage reference circuit, Robert Dobkin and Robert Widlar.

1966, US Patent 3271660, Reference voltage source, David Hilbiber.

Bandgaps are also suited for low-power applications. 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. However, the parabolic characteristic of voltage versus temperature means that a single figure in ppm/☌ does not adequately describe the behaviour of the circuit. Temperature coefficients as low as 1.5–2.0ppm/☌ can be obtained with bandgap references.

This temperature dependency has a typical parabolic residual behavior since the linear (first order) effects are chosen to cancel.ĭespite these limitations, the bandgap voltage reference is widely used in voltage regulators, covering the majority of 78xx, 79xx devices along with the LM317, LM337 and TL431 devices. The remaining voltage change over the operating temperature of typical integrated circuits is on the order of a few millivolts. The resulting voltage is about 1.2–1.3V, depending on the particular technology and circuit design, and is close to the theoretical 1.22eV bandgap of silicon at 0K. 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. The voltage across a diode operated at constant current is complementary to absolute temperature ( CTAT), with a temperature coefficient of approximately −2mV/K. This voltage in turn is added to the voltage of one of the junctions (or a third one, in some implementations).

This current is used to generate a voltage in a second resistor. diodes), operated at different current densities, is used to generate a current that is proportional to absolute temperature ( PTAT) in a resistor. The voltage difference between two p–n junctions (e.g.

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