![]() ![]() 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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