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Topic: Widlar current source

	Modified widlar source and logic circuit using same - Patent 5309044 (Site not responding. Last check: 2007-11-05)
		Portion 51a comprises a resistor 55a, an NPN transistor 56a, a resistor 57a, an NPN transistor 58a, and a current source 59a.
		Portion 61a comprises a resistor 62a, an NPN transistor 63a, a resistor 64a, an NPN transistor 65a, a current source 66a, an NPN transistor 67a, and a current source 68a.
		Portion 120 comprises NPN transistors 122-124, resistors 125 and 126, an NPN transistor 127, a current source 128, a P-channel transistor 129, an NPN transistor 130, and a current source 131.
	www.freepatentsonline.com /5309044.html (7617 words)

	Widlar current source - Wikipedia, the free encyclopedia
		A Widlar current source is a current source attributed to the late Bob Widlar, in which an emitter degeneration resistor is only applied to Q
		The current source is commonly used to generate low currents.
		Hence the circuit must be driven by a constant current source instead of R1 to keep the output current constant.
	en.wikipedia.org /wiki/Widlar_current_source (218 words)

	ami4409_amsicd -u01: Bipolar Transistor Characteristics and Current Source Design
		Consideration is then given to the design of current sources and mirrors which are used extensively for biasing purposes and as active loads in high gain amplifiers.
		Current conduction, for a given applied base-emitter voltage, is really determined by the size (area) of the emitter.
		More complex current source designs are aimed at improving either static and/or dynamic accuracy but this is often at the cost of providing a much worse minimum output voltage.
	www.ami.ac.uk /courses/ami4409_amsicd/u01/index.asp (2549 words)

	Current source - Wikipedia, the free encyclopedia
		A current source is the dual of a voltage source.
		An ideal current source is a conceptual source used in network theory and analysis that delivers or absorbs electrical energy such that the electrical current is independent of the voltage across its terminals.
		Current sources are often used in place of resistors in analog integrated circuits to generate a current without causing attenuation at a point in the signal path to which the current source is attached.
	en.wikipedia.org /wiki/Current_source (1369 words)

	What's All This Widlar Stuff, Anyhow? (Site not responding. Last check: 2007-11-05)
		When we got the word that Bob Widlar had passed away on February 27, 1991, at the young age of 53, (heck, I'll be up there at 53 in a couple years, if I'm lucky...), we all began to bring out stories about things Widlar had done.
		Widlar was as good-natured as he could be, and I finally broke the habit -- after about a week of reminders.
		Widlar, being a curious sort, decided to PUSH where it was indicated.
	www.national.com /rap/Story/widlar.html (2837 words)

	Field effect transistor current source - Patent 4645948 (Site not responding. Last check: 2007-11-05)
		The present invention also provides that the current source FET may be fabricated by the same fabrication process (e.g., on the same semiconductor substrate) as the circuits utilizing the controlled current.
		In other current sources there is no connection between these two; even when the worst-case assumption of high current is made, it is not as high as it is in the self-compensating source.
		For a wafer with a measured DL=0.22.mu.m, the calculated current was 105% nominal, and the measured current was 114% of the nominal.
	www.freepatentsonline.com /4645948.html (4687 words)

	EDN -- 02.15.96 Peaking current source has high rejection (Site not responding. Last check: 2007-11-05)
		Peaking current sources are those with a characteristic operating point for which the output current is independent of the input current.
		However, this single peaking source exhibits a relatively narrow region for which the output is independent of the input current.
		The cascade peaking source achieves significant improvement in output-current regulation compared with the conventional and Widlar current sources (Figure 4b) but imposes only a minor increase in circuit complexity (one additional resistor compared to the Widlar source and two additional resistors compared to the conventional source).
	www.edn.com /archives/1996/021596/04df4.htm (603 words)

	wilson current source
		Variations to the basic current mirror are the Widlar current source and the Wilson current source.
		The current stadium is open-air, with a capacity of 73,967, with an...
		Wilson worked in the CIA's As for his current implication that he [Armitage] never expected this to be published, claimed first realization that he was unable to verify the claim, [ SOURCE : (c)2006 Los Angeles Times].
	www.electronicsee.com /wilson-current-source (723 words)

	Analog Electronics 2004 - Contents
		Applications: producing a current from a voltage (compound voltage-controlled current source); indirect measuring a voltage by converting into a current (compound voltmeter); transistor switch (an input part); current interface (a transmitter).
		Applications: producing a current controlled by a resistance (compound resistance-controlled current source); indirect measuring a resistance by converting into a current (compound ohmmeter); indirect measuring non-electrical quantities by resistive sensors.
		Applications in analog circuitry: building a transistor amplifier from electrically controlled current source and current-to-voltage converter; dynamic load in differential amplifiers; ramp generator - building the circuit by means of transistor current source and C integrator.
	www.circuit-fantasia.com /my-students/ske2004/classes/contents-ske.htm (2995 words)

	741 Op-Amp Tutorial, op-amps, Operational Amplifier
		The first solid-state monolithic op-amp, designed by Bob Widlar, offered to the public in 1963 was the uA702 manufactured by Fairchild Semiconductors but it had very weird supply voltages such as +12 and -6 volts and had a tendency to burn out when it was temporarily shorted.
		Widlar worked briefly in 1980 for Linear Technology and continued to produce designs for National Semiconductors on a consulting basis for the rest of his life.
		Under the brilliant guidance and futuristic view again of Bob Widlar, National Semiconductor decided to jump on the bandwagon with the release of a more versatile op-amp version in the form of the LM101 in 1967.
	www.uoguelph.ca /~antoon/gadgets/741/741.html (4734 words)

	[No title]
		The emitter current from Q4 is due to the fact that Q3 is still off and all the current from the current source is being forced into the base of Q4 which in-turn becomes its emitter current.
		We didn’t use cascoding in the first stage of the current source because of the extra Vbe drops that would be needed to do that, limiting the current source bias voltage.
		To measure the output impedance of the circuit an ideal current source was connected to the output with AC = 1.
	web.pdx.edu /~tim/classes/ece421/ECE_421project.doc (3720 words)

	Radio Currents Online - Oct 24 - Oct 30, 2005
		In the suspenseful last moments of the auction, the winning bid was nearly placed by the son of one of the original Model 43 design engineers, Jim Widlar, who was seeking to commemorate his father's contribution to the development of the product.
		Widlar, whose father Walt Widlar worked with J. Raymond Bird and the Model 43 design team in the early 1950s, lost the auction to an anonymous bidder at the last minute.
		Many Edge libraries are currently available on www.prosoundeffects.com and the entire catalog is expected to be added in the coming weeks.
	beradio.com /currents/radio_currents_102405/index.html (3047 words)

	ultranalog: coldwar
		A transistor may be used as the current source at the cathode of the 5670, thus requiring no negative power supply.
		I altered the driver stage from the NiCd biased longtailed pair to a Widlar CCS longtailed pair.
		The Widlar current source shows better thermal stability since the equal devices mutually compensate for their increase in temperature.
	ultranalog.com /coldwar (854 words)

	Circuit engineering - Constant Current Source
		There is a very easy way to build a two-terminal current source using a pair complementary bipolar transistors, two zener-diodes (or other voltage references) and a few resistors.
		A Howland current source can be made to achieve 2% accuracy, but you need an Opamp with the divider and feedback resistors on the silicon with the Opamp.
		But, you'd be able to accommodate the voltage range and the current range, particularly if you use a programmable current source as the reference current.
	www.eng-tips.com /viewthread.cfm?qid=41439 (1134 words)

	Analyzing the IC555 inner circuit
		It seems that there are two current mirrors, but the left one doesn’t have a path for the “reference” current to flow, because the Darlington transistors aren’t active (they are cut) since there’s no voltage at the Threshold pin.
		Now, theoretical current mirrors have a “normal” path for the reference current (normally a resistor), so we can obtain easily the reference current.
		Thats true that the emitter current of Q1 may not be negligible, which forms the base current of Q2, but here we are not neglecting that current.
	www.edaboard.com /viewtopic.php?p=468056 (1266 words)

	ECE3220 Quiz #4 Prep Sheet (Site not responding. Last check: 2007-11-05)
		Determine the current transfer ratio for a given Widlar current source.
		Determine the component sizes needed to achieve a desired current transfer ration in a Widlar current source.
		In a discrete transistor current mirror (as an example) there is a phenomenon known as thermal runaway that can occur.
	web.uccs.edu /wbahn/ECE3220/quiz04prep.htm (315 words)

	Amazon.com: Current Sources and Voltage References: A Design Reference for Electronics Engineers: Books: Linden T. ... (Site not responding. Last check: 2007-11-05)
		Current sources and voltage references provide fixed, well-regulated levels of current or voltage within a circuit.
		Part 1 shows the reader how current sources are created, how they can be optimized, and how they can be utilized by the OEM circuit designer.
		Current sources and voltage references both depend on inherent characteristics of the transistor, either the bipolar junction transistor (BJT) or the field-effect transistor (FET), in order to operate properly.
	www.amazon.com /Current-Sources-Voltage-References-Electronics/dp/075067752X (1083 words)

	[No title]
		Figure 2 is a schematic diagram of a simple current source.
		Measure at 1 ma and at 50 mA collector currents in the forward active region.
		Figure 3 is a schematic diagram of a Widlar current source.
	www.d.umn.edu /~sburns/ECE2212Spring2004/Experiment8CurrentSources.htm (481 words)

	Untitled Document
		A single resistor or current source is all that is needed to set the supply current to the minimum required for a given speed.
		Current consumption is one thirtieth of the inveterate 555, peaking at 150µA (6V) and dropping to under 60µA (1V).
		The current sourcing part of the output is shown in (green).
	www.g8ajn.tv /n_clips.htm (13364 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		The wilson current mirror pulls a bit current because the transistors source-drain voltage is not equal, and then the way as usal is to cascade it (making voltage equal).
		Total, the current is very low, and as on all flash converters, is no clock input needed.
		The bad characteristic for Widlar current mirrors have been improved to cut off for low current, and thereby decrease the offset currents.
	www.jdm.homepage.dk /ad.htm (485 words)

	Midterm Review (Site not responding. Last check: 2007-11-05)
		The basic exponential equation that describes the collector current as a function of base-emitter voltage in a BJT - a.k.a.
		The determination of the current transfer ratio for the basic current mirrors and sources.
		The determination of the output resistance of the basic current mirrors and sources.
	web.uccs.edu /wbahn/ECE3220/exam1rev.htm (1168 words)

	[No title]
		For the Widlar current source in Figure 5, find IREF and RE for and output current I of 200 (A. Use VCC = 15 V. Read the data sheets of the LM334.
		The 3-terminal current source LM334 is used to maintain a constant IB.
		In your circuit, adjust the current source to obtain VCE1.
	w3.uwyo.edu /~evafp/ee3330/lab4.doc (1328 words)

	[No title]
		Include a SPICE simulation of the I-V output characteristics for both current sources.
		The data sheet was distributed in support of the Current Source Experiment.
		Measure the all Q-point voltages and currents using the DMM.
	www.d.umn.edu /~sburns/ECE2212Fall2005/Experiment8CurrentSources.htm (1130 words)

	Brian Hood
		We decided to use a Widlar current source for the differential amplifier.
		Our first current source didn’t supply enough current for the differential stage, so the output was clipped at the positive rail.
		We tried a few different resistor values for the current source until the output stopped clipping.
	www.ee.calpoly.edu /~dbraun/courses/ee308/W99/1_10/1_10.htm (199 words)

	Custom ASICS and BiPolar Analog Arrays
		Use these when you need a current source, but the value us not important (see the Design Manual).
		These act like small resistors, so it is a preference to use these on lower current nodes (a base connection is preferrable to an emitter connection.
		These are current supplies that need to be set up with one of the example circuits.
	www.deiaz.com /asics/example_circuit_sizes.htm (322 words)

	Circuit Sage: Bandgap Tools and Links
		Widlar, IEEE J. Solid-State Circuits, SC-6, 2-7, 1971.
		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.
	www.circuitsage.com /bandgap.html (354 words)

	ECE3220 Quiz #3 Prep Sheet (Site not responding. Last check: 2007-11-05)
		Draw a BJT-based current mirror having base current compensation of both the NPN and the PNP variety.
		Draw a BJT-based Widlar current source of both the NPN and the PNP variety.
		Derive the current gain and output resistance of BJT-based Widlar current source.
	web.uccs.edu /wbahn/ECE3220/quiz03prep.htm (277 words)

	Problem 4.5
		resistor is used to decrease current level (Widlar current source).
		is small; of course, we need to validate this assumption after solving this problem, that is that the current in Q
		, where V is the middle node of the current source.
	users.ece.gatech.edu /phasler/Courses/ECE4430/Unit2/Prob4-5.html (91 words)

	Custom ASICS and BiPolar Analog Arrays
		For the low input impedance application such as measuring a low current, the input impedance can be on the order of 500 ohms.
		In fact, the lower the input current, the lower the operating current for a differential stage, and the higher you need for input impedance.
		In order to measure a high input current and use low power techniques, the designer can attenuate the input and run at lower currents.
	www.deiaz.com /asics/700_Series_FAQs.htm (1912 words)

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