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Topic: Bandgap voltage reference

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	Monolithic CMOS digital temperature measurement circuit - Patent 4165642
		A voltage charging network connected to the substrate of one of the input transistors adjusts the substrate voltage during an auto-zero cycle and thereby the threshold voltage of the input transistor and the balancing amplifier.
		The bandgap voltage reference circuit 18 has an output line 38 connected to the A to D converter 12, and is connected to the control logic 20 via a connection 40.
		The negative temperature reference voltage output 124 is similarly generated by scaling the positive temperature coefficient voltage over one additional resistor 112 in addition to the resistors 114 and 116 and adding to the V.sub.BE of two additional parasitic transistors 126 and 128 which have their emitters connected to two current sources 130 and 132.
	www.freepatentsonline.com /4165642.html (5529 words)

	Low voltage bandgap reference (bgr) circuit invention
		These reference voltages are coupled to amplifying circuits which generate reference voltages with equal and opposite temperature coefficients based on the ratio of resistors in these amplifying circuits, thereby producing a temperature independent reference voltage.
		The bandgap reference voltage generator includes a multitude of output stages where each output may be independently scaled to have either a zero, a positive or a negative temperature coefficient.
		Secondly, these two reference voltages are driving a summing circuit, each using current sources and resistive means to generate a current which is dependent on the ratio of the positive reference voltage and a resistive means, and the ratio of the negative reference voltage and another resistive means.
	www.freshpatents.com /Low-voltage-bandgap-reference--bgr--circuit-dt20060817ptan20060181335.php (2111 words)

	Dual stage voltage regulation circuit invention
		The feedback loop employs a bandgap reference source feeding a comparator, with an output driver transistor drawing current from a common supply and having an output electrode connected to a voltage divider, allowing a sample of the output to be fed back to the comparator to maintain the desired output voltage.
		A first reference voltage is applied at a node between the two capacitors and a second reference voltage to a comparator, which controls the operation of the charge pump.
		When the bandgap voltage exceeds the signal at terminal 41, the comparator is enabled producing a voltage related to the bandgap voltage on output line 19 which controls gate 21 of the p-type enhancement MOS transistor 23.
	www.freshpatents.com /Dual-stage-voltage-regulation-circuit-dt20060824ptan20060186869.php (1818 words)

	U.S. Patent: 5132556 - Bandgap voltage reference using bipolar parasitic transistors and MOSFET's in the current ...
		A bandgap voltage reference as in claim 1, wherein said first and second parasitic bipolar transistors are lateral NPN transistors, said third parasitic bipolar transistor is a vertical NPN transistor, and said first and second MOSFET transistors are p-channel MOSFET transistors.
		A bandgap reference as in claim 2, wherein the respective first semiconductor regions of said first and second bipolar transistors are overlaid by respective insulated gates, said insulated gates being biased below their respective threshold voltages to create respective accumulation layers in the first semiconductor regions of said first and second bipolar transistors.
		A bandgap reference circuit as in claim 10, wherein the circuit portion comprising said first and second cascode CMOS amplifiers is of a symmetrical design, and said first, second, third and fourth MOS transistors are large area transistors.
	www.everypatent.com /comp/pat5132556.html (3418 words)

	Low-voltage, buffered bandgap reference with selectable output voltage invention
		Voltage references that can produce a stable, temperature-independent reference of less than the semiconductor bandgap voltage may be useful in combination with these circuits.
		3 is a temperature-independent voltage reference according to an embodiment of the invention.
		The op amp 300 is an active component that compares the voltages of the two voltage dividers and produces an output signal that, because of the feedback loop in the circuit, is a temperature-independent reference voltage whose value is set according to the selection of the resistors.
	www.freshpatents.com /Low-voltage-buffered-bandgap-reference-with-selectable-output-voltage-dt20061228ptan20060290415.php (1822 words)

	Bandgap voltage reference circuit with high power supply rejection ratio (PSRR) and curvature correction - Patent ...
		A bandgap voltage reference circuit according to claim 5 wherein the values of the first and second resistors are equal, thereby ensuring that the transistors of the second stacked transistor pair operate with PTAT currents.
		A bandgap voltage reference circuit according to claim 12 wherein the second set of circuit components further includes a fifth resistor coupled between the first set of current mirrors and ground, the first, second and fifth resistors adapted to provide the temperature curvature correction of the output voltage.
		However one of the problems associated with this traditional voltage reference circuit is that although the bandgap voltage output is independent of temperature to a first order, the output of this standard circuit is found to include a term that varies with TlnT, where T is absolute temperature and "In" is the natural logarithm function.
	www.freepatentsonline.com /6891358.html (3946 words)

	Bandgap voltage reference circuit and method with low TCR resistor in parallel with high TCR and in series with low TCR ...
		The bandgap voltage reference circuit of claim 9, wherein the ratio of resistance values between said third and fourth resistors is selected so that, as a function of temperature, the rate of change in said output voltage both with and without said third and fourth resistors is substantially zero at approximately the same temperature.
		Bandgap reference circuits have been developed to provide a stable voltage supply that is insensitive to temperature variations over a wide temperature range.
		The voltages at the opposite sides of RL1 and RL2 from V+ are maintained at the same constant voltage levels by connecting these points respectively to the non-inverting and inverting inputs of an operational amplifier 2, the output of which is connected to the cell's output terminal 4.
	www.freepatentsonline.com /5291122.html (3959 words)

	Bandgap voltage reference - Article from FactBug.org - the fast Wikipedia mirror site
		A bandgap voltage reference is a voltage reference circuit widely used in integrated circuits, usually with an output voltage around 1.25 V, close to the theoretical bandgap of silicon at 0 K. The operation principle of bandgap voltage references is in principle simple.
		The resulting voltage is about 1.2–1.3 V, depending on the particular technology, and is close to the theoretical 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.
		Since 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 drain-source voltage of a FET (field effect transistor) has to be added.
	www.factbug.org /cgi-bin/a.cgi?a=516067 (341 words)

	Bandgap voltage reference generator - Patent 5453953
		A voltage regulator is provided for controlling an on-chip voltage generator which produces a boost voltage across a charge reservoir for supply to one input of a plurality of word line drivers in a memory array.
		The voltage supply circuitry includes first supply means for providing a first voltage to the first inputs of the plurality of word line drivers and second supply means for supplying a second voltage to the second inputs of the word line drivers.
		The reference voltage to be output from the generator comprises the voltage at the coupled gate and drain of the heavily doped P-type polysilicon PMOS transistor.
	www.freepatentsonline.com /5453953.html (4046 words)

	Line regulator with high bandwidth (BW) and high power supply rejection ration (PSRR) and wide range of output current ...
		The IC 202 may comprise a reference amplifier 204, a plurality of reference transistor devices 206, and 208, a plurality of resistors 218 and 220, a capacitor 222, a decoupling capacitor C.sub.decouple 238, an operational transconductance amplifier (OTA) 226, an output transistor device 228, an IP core 240, and a ground reference 224.
		A bandgap reference voltage may be characterized by a voltage level that may remain constant with less variation due to changes in device operating temperature than may be observed in other voltage source circuit designs.
		The drain current for reference transistor 208 may be represented as: i.sub.dr208=g.sub.m208v.sub.GS208 equation[7] where, i.sub.dr208 may represent the drain current of the transistor 208, g.sub.m208 may represent the transconductance of the transistor 208, and v.sub.gs208 may represent the gate to source voltage of the transistor 208.
	www.linkgrinder.com /Patents/Line_regulator__7212043.html (7899 words)

	Selecting the Optimum Voltage Reference - Maxim/Dallas
		In a voltage regulator, a reference provides a known value which is compared to the output to develop the feedback that is used to regulate the output voltage.
		The key differences between a shunt and series reference is that the three terminal series-mode voltage references do not require an external resistor and have significantly lower quiescent power.
		Most applications require a voltage reference to source current to the load(s) and of course, the reference needs to be able to supply the required load current.
	www.maxim-ic.com /appnotes.cfm/an_pk/2879 (1503 words)

	A low-power bandgap voltage reference
		A bandgap reference is an example of a low frequency application where accuracy and area give constraints on the total power consumption.
		In mixed level applications accurate voltage references are difficult to realize due to the lack of reproducible lateral pnp transistors and the large offsets inherent to CMOS opamps.
		denotes the extrapolated bandgap voltage of a semiconductor,
	www10.pcbcafe.com /book/phdThesis/Chapter-5.7.php (1020 words)

	EETimes.com - Temperature-aware design for mixed-signal ICs
		The bandgap produces a voltage that is meant to be temperature-independent by adding a voltage that increases with temperature of the bandgap circuit elements — called the proportional-to-absolute-temperature or PTAT — to a voltage that decreases with temperature, called complementary-to-absolute-temperature or CTAT.
		The CTAT voltage is generated by tapping the forward-biased base-emitter junction of a bipolar transistor while the PTAT voltage is generated by using the difference in the base-emitter voltages of two bipolar transistors, one of which is larger than the other, although both the bipolar transistors carry the same total current.
		At lower reference voltages, temperature effects are stronger and extra circuitry is needed to compensate for the higher-order temperature dependency.
	www.eetimes.com /showArticle.jhtml?articleID=186700044&pgno=2 (1012 words)

	Circuit Sage: Bandgap Tools and Links
		Bob Pease, "The design of Band-Gap Reference Circuits: Trials and Tribulations," IEEE Proceedings of the 1990 Bipolar Circuit and Technology Meeting, September 17-18th 1990.
		Effect of Ground Drop on Bandgaps, by Jim Daly: a case for routing bandgap currents and Kelvin connections.
		Statistical analysis of a bandgap reference from Zkom.
	www.circuitsage.com /bandgap.html (354 words)

	BG001 - Untrimmed Precision Bandgap Voltage/Current Reference
		(1) Although the bandgap may be implemented in any of the C5x processes, it should be noted that due to differences in sheet resistance between single polysilicon, double polysilicon, and high resistivity polysilicon processes, the bandgap output voltage may shift and will need to be recentered.
		Two of the most common questions regarding Bandgap performance are “what is the tolerance” and “what is the temperature Coefficient?” There are two important things to consider when talking about bandgap tolerance.
		Regarding voltage at a given temperature, if one were to choose a random part “off the shelf” for this bandgap circuit and measure the voltage at room temperature, it would be 1.226V +/-21mV.
	www.amis.com /tech_resources/tech_docs/featuresheets/bg001/index.html (640 words)

	A low-power bandgap voltage reference
		A bandgap reference is an example of a low frequency application where accuracy and area give constraints on the total power consumption.
		In mixed level applications accurate voltage references are difficult to realize due to the lack of reproducible lateral pnp transistors and the large offsets inherent to CMOS opamps.
		denotes the extrapolated bandgap voltage of a semiconductor,
	www.edatoolscafe.com /books/phdThesis/Chapter-5.7.php (1049 words)

	Voltage reference takes digital control onboard: News from Xicor
		The X60250 is a fully integrated digitally adjustable voltage reference that combines a temperature compensated bandgap voltage reference with a nonvolatile digitally controlled potentiometer (DCP) to provide a precision adjustable reference with a range of 0.0 to 1.25V.
		The reference voltage is changed by addressing the 256-tap DCP via a bidirectional two-wire serial bus.
		The reference voltage setting is retained in the internal nonvolatile memory when power is disconnected and the power-on-recall circuit restores the X60250 to the stored voltage on power-up.
	www.electronicstalk.com /news/xic/xic134.html (606 words)

	CiteULike: A sub-1-V 15-ppm/°C CMOS bandgap voltage reference without requiring low threshold voltage device (Site not responding. Last check: 2007-10-02)
		A sub-1-V CMOS bandgap voltage reference requiring no low threshold voltage device is introduced in this paper.
		≈ 0.9 V at 0°C, the minimum supply voltage of the proposed voltage reference is 0.98 V, and the maximum supply current is 18 μA. A temperature coefficient of 15 ppm/°C from 0°C to 100°C is recorded after trimming.
		\≈ 0.9 V at 0\°C, the minimum supply voltage of the proposed voltage reference is 0.98 V, and the maximum supply current is 18 \μA. A temperature coefficient of 15 ppm/\°C from 0\°C to 100\°C is recorded after trimming.
	www.citeulike.org /user/summerxia/article/834188 (205 words)

	humancompetitive
		The voltage supplied by all practical sources of electrical power is subject to variation.
		However, many circuits operate properly only when they are supplied with one or more reference voltages that can be relied upon to vary only slightly from their specified values.
		A voltage reference circuit supplies a prespecified constant voltage (with a small prespecified tolerance) in spite of variation in the incoming power supply and in spite of variation in the ambient temperature.
	www.genetic-programming.com /hc/voltagereference.html (771 words)

	Power Management DesignLine \| Inside the Belly of the Beast: A Map for the Wary Bandgap Reference Designer when ...
		A "bandgap" produces a voltage that is temperature independent by adding a voltage that increases with temperature, i.e., has proportional-to-absolute-temperature or PTAT dependence, to a voltage that decreases linearly with temperature, i.e., has complementary-to-absolute-temperature or CTAT dependence, as shown in Figure 1.
		Most bandgap references are based on the circuit presented in the classical paper by Brokaw in 1974 [1].
		Package shift, though not the largest contributor to the overall inaccuracy of a bandgap reference, is an important source of error because it results after the device is packaged, requiring exotic packaging solutions and/or post-package trimming techniques.
	www.powermanagementdesignline.com /showArticle.jhtml?articleID=60402040 (1808 words)

	A Low Noise CMOS Voltage Reference - Holman (ResearchIndex)
		By nature these low noise voltage references are not sensitive to temperature or supply variations and could be used for comparison...
		1 A CMOS Voltage Reference (context) - Tsividis, Ulmer - 1978
		1 A Low-Voltage CMOS Bandgap Reference (context) - Vittoz, Neyroud - 1979
	citeseer.ist.psu.edu /holman94low.html (965 words)

	Wiley-IEEE Press::Voltage References: From Diodes to Precision High-Order Bandgap Circuits
		Voltage References: From Diodes to Precision High-Order Bandgap Circuits
		Voltage References covers the conceptual history and scope of practical design issues behind marketable and precision integrated voltage references.
		Voltage References is an essential book for IC designers, product engineers, test engineers, researchers, and professors, as well as undergraduate and graduate students.
	www.wiley.com /WileyCDA/WileyTitle/productCd-0471143367,miniSiteCd-IEEE2.html (286 words)

	CiteULike: Design considerations of recent advanced low-voltage low-temperature-coefficient CMOS bandgap voltage ... (Site not responding. Last check: 2007-10-02)
		The design considerations of CMOS bandgap voltage references, focusing on low-voltage and low-temperature-coefficient methodologies, are discussed in this paper.
		Some recently reported circuits of bandgap voltage references are included and analyzed.
		Moreover, a CMOS voltage reference is also addressed.
	www.citeulike.org /user/summerxia/article/834189 (192 words)

	August 2002 EEELinks (Site not responding. Last check: 2007-10-02)
		It can be seen that the reference output voltage generally remains within specifications (2.499 to 2.501 V) between temperatures of 25 °C to -40 °C. Below -40 °C, however, the output voltage begins to fluctuate as the temperature is decreased.
		While the output voltage undergoes a slight increase with decrease in temperature for the no-load condition, it exhibits a decrease when a load is applied.
		It can be seen that the reference output voltage remains within specifications (2.499 to 2.501 V) between temperatures of 25 °C to -40 °C. Between -40 °C and -120 °C, however, the output voltage begins to decrease very slowly as the temperature is decreased.
	nepp.nasa.gov /eeelinks/August2002/cryo3.htm (1598 words)

	Power Management DesignLine \| How to improve linear regulator power supply ripple rejection and output noise (Site not responding. Last check: 2007-10-02)
		The PSRR of the bandgap voltage reference, whose output ripple affects the output ripple of the linear regulator up to the roll-off frequency of the bandgap.
		The PSRR of the bandgap is a critical contributor to the PSRR of the linear regulator up to the bandgap’s roll-off frequency, since any bandgap output ripple is amplified by the error amplifier, which in turn propagates the amplified ripple through the pass element to V
		In addition to having a bandgap with high intrinsic PSRR, it is a common practice to “bypass” its output ripple to the ground through a low-pass filter before it reaches the error amplifier input.
	www.powermanagementdesignline.com /news/184401056 (690 words)

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