`
`Bandgap voltage reference
`
`Bandgap voltage reference Wikipedia
`
`From Wikipedia, the free encyclopedia
`
`A bandgap voltage reference is a temperature independent voltage reference circuit widely used in integrated
`circuits. It produces a fixed (constant) voltage regardless of power supply variations, temperature changes and
`circuit loading from a device. It commonly has an output voltage around 1.25 V (close to the theoretical 1.22 eV
`bandgap of silicon at 0 K). This circuit concept was first published by David Hilbiber in 1964.[1] Bob Widlar,[2]
`Paul Brokaw[3] and others[4] followed up with other commercially successful versions.
`
`Contents
`
`1 Operation
`2 Patents
`3 See also
`4 References
`5 External links
`
`Operation
`
`The voltage difference between two pn junctions (e.g. diodes), operated at
`different current densities, is used to generate a proportional to absolute
`temperature (PTAT) current in a first resistor. This current is used to
`generate a voltage in a second resistor. This voltage in turn is added to the
`voltage of one of the junctions (or a third one, in some implementations).
`The voltage across a diode operated at constant current, or here with a
`PTAT current, is complementary to absolute temperature, with
`approximately −2 mV/K. 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 resulting voltage is about
`1.2–1.3 V, depending on the particular technology and circuit design, and is
`close to the theoretical 1.22 eV bandgap of silicon at 0 K. The remaining
`voltage change over the operating temperature of typical integrated circuits
`is on the order of a few millivolts. This temperature dependency has a
`typical parabolic residual behavior since the linear (first order) effects are
`chosen to cancel.
`
`Circuit of a Brokaw bandgap
`reference
`
`Because the output voltage is by definition fixed around 1.25 V for typical bandgap reference circuits, the
`minimum operating voltage is about 1.4 V, as in a CMOS circuit at least one drainsource voltage of a FET (field
`effect transistor) has to be added. Therefore, recent work concentrates on finding alternative solutions, in which for
`example currents are summed instead of voltages, resulting in a lower theoretical limit for the operating voltage
`(Banba, 1999).
`
`Note that sometimes confusion arises when using the abbreviation CTAT, where the "C" is incorrectly taken to
`mean "constant" rather than "complementary". To avoid this confusion, although not in widespread use, the term
`constant with temperature (CWT) is sometimes used.
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`When summing a PTAT (Proportional to Absolute Temperature) and a
`CTAT (Complementary to Absolute Temperature) current, only the linear
`terms of current are compensated, while the higherorder terms are limiting
`the TD (Temperature Drift) of the BGR at around 20ppm/oC, over a
`temperature range of 100 oC. For this reason, in 2001, Malcovati [5]
`designed a circuit topology that can compensate highorder nonlinearities,
`thus achieving an improved TD. This design used an improved version of
`Banba [4] topology and an analysis of baseemitter temperature effects that
`was performed by Tsividis in 1980.[6] In 2012, Andreou [7] [8] has further
`improved the highorder nonlinear compensation by using a second opamp
`along with an additional resistor leg at the point where the two currents are
`summed up. This method enhanced further the curvature correction and
`achieved superior TD performance over a wider temperature range. In
`addition it achieved improved line regulation and lower noise.
`
`Characteristic and balance point of T1
`and T2
`
`The other critical issue in design of bandgap references is power efficiency and size of circuit. 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. Moreover, this type of circuit might consume a lot of power to reach to the desired noise
`and precision specification.[9]
`
`Despite 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. Temperature coefficients as low as 1.5
`2.0 PPM/°C can be obtained with bandgap references (LT6657 from Linear Technology and ADR4550 from
`Analog Devices). Bandgaps are also suited for lowpower applications (1 µA cathode current with the Maxim
`Integrated MAX6009 shunt voltage reference).
`Patents
`
`1966, US Patent 3271660, Reference voltage source, David Hilbiber.[10]
`1971, US Patent 3617859, Electrical regulator apparatus including a zero temperature coefficient voltage
`reference circuit, Robert Dobkin and Robert Widlar.[11]
`1981, US Patent 4249122, Temperature compensated bandgap IC voltage references, Robert Widlar.[12]
`1984, US Patent 4447784, Temperature compensated bandgap voltage reference circuit, Robert Dobkin.[13]
`See also
`
`Brokaw bandgap reference
`LM317
`Silicon bandgap temperature sensor
`References
`
`1. Hilbiber, D.F. (1964), "A new semiconductor voltage
`standard", 1964 International SolidState Circuits
`Conference: Digest of Technical Papers, 2: 32–33,
`doi:10.1109/ISSCC.1964.1157541
`2. Widlar, Robert J. (February 1971), "New Developments
`in IC Voltage Regulators", IEEE Journal of SolidState
`Circuits, 6 (1): 2–7, doi:10.1109/JSSC.1971.1050151
`
`3. Brokaw, Paul (December 1974), "A simple three
`terminal IC bandgap reference", IEEE Journal of Solid
`State Circuits, 9 (6): 388–393,
`doi:10.1109/JSSC.1974.1050532
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`4. Banba, H.; Shiga, H.; Umezawa, A.; Miyaba, T.;
`9. A. Tajalli, et al. ,"Design and optimization of a high
`Tanzawa, T.; Atsumi, S.; Sakui, K. (May 1999), "A
`PSRR CMOS bandgap voltage reference," IEEE
`CMOS bandgap reference circuit with sub1V
`ISCAS 2004 DOI: 10.1109/ISCAS.2004.1328127 [1] (h
`operation", IEEE Journal of SolidState Circuits, 34
`ttp://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=13
`(5): 670–674, doi:10.1109/4.760378
`28127&url=http%3A%2F%2Fieeexplore.ieee.org%2Fx
`5. P. Malcovati, F. Maloberti, C. Fiocchi, and M. Pruzzi,
`pls%2Fabs_all.jsp%3Farnumber%3D1328127)
`10. US Patent 3271660 Reference voltage source, David F
`“Curvaturecompensated bicmos bandgap with 1V
`supply voltage,” IEEE J. SolidState Circuits, vol. 36,
`Hilbiber; United States Patent and Trademark Office;
`no. 7, pp. 1076–1081, Jul. 2001.
`September 6, 1966. (https://www.google.com/patents/U
`6. Y. P. Tsividis, “Accurate analysis of temperature effects
`S3271660)
`11. US Patent 3617859 Electrical regulator apparatus
`in IcVbe characteristics with application to bandgap
`including a zero temperature coefficient voltage
`reference sources,” IEEE J. SolidState Circuits, vol.
`reference circuit; Robert C Dobkin and Robert J
`15, no. 6, pp. 1076 – 1084, Dec. 1980.
`7. C. M. Andreou, S. Koudounas, and J. Georgiou, “A
`Widlar; United States Patent and Trademark Office;
`November 2, 1971. (https://www.google.com/patents/U
`Novel WideTemperatureRange, 3.9ppm/oC CMOS
`S3617859)
`Bandgap Reference Circuit,” IEEE Journal of Solid
`12. US Patent 4249122 Temperature compensated
`State Circuits, vol.47, no. 2, pp. 574–581, Jan. 2012,
`bandgap IC voltage references; Robert J Widlar; United
`doi:10.1109/JSSC.2011.2173267 (http://ieeexplore.ieee.
`States Patent and Trademark Office; February 3, 1981.
`org/xpl/login.jsp?tp=&arnumber=6078439&url=http%3
`(https://www.google.com/patents/US4249122)
`A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%
`13. US Patent 4447784 Temperature compensated
`3Farnumber%3D6078439)
`bandgap voltage reference circuit; Robert C Dobkin;
`8. S. Koudounas, C. M. Andreou and J. Georgiou, ”A
`United States Patent and Trademark Office; May 8,
`Novel CMOS Bandgap Reference Circuit with
`1984. (https://www.google.com/patents/US4447784)
`Improved HighOrder Temperature Compensation,”
`IEEE International Symposium on Circuits and
`Systems (ISCAS), Paris, France,2010 pp. 40734076,
`doi:10.1109/ISCAS.2010.5537621 (http://ieeexplore.iee
`e.org/xpl/login.jsp?tp=&arnumber=5537621&url=http%
`3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.js
`p%3Farnumber%3D5537621)
`External links
`
`The Design of BandGap Reference Circuits: Trials and Tribulations (http://www.ti.com/ww/en/bobpease/as
`sets/wwwnationalcom_rap.pdf) p.286 – Robert Pease, National Semiconductor
`Features and Limitations of CMOS Voltage References (http://ecad.tusofia.bg/et/1999/Statii%20ET99I/Fea
`tures%20and%20Limitations%20of%20CMOS%20Voltage%20References.pdf)
`ECE 327: LM317 Bandgap Voltage Reference Example (http://www.tedpavlic.com/teaching/osu/ece327/lab
`3_vreg/lab3_vreg_lm317_example.pdf) – Brief explanation of the temperatureindependent bandgap
`reference circuit within the LM317.
`
`Retrieved from "https://en.wikipedia.org/w/index.php?title=Bandgap_voltage_reference&oldid=757334118"
`
`Categories: Electronic circuits Analog circuits
`
`This page was last modified on 30 December 2016, at 02:48.
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`https://en.wikipedia.org/wiki/Bandgap_voltage_reference
`
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`
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`Polaris Ex. 2004
`
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