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Bandgap Voltage Reference
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, or circuit loading from a device. It commonly has an output voltage around 1.25V (close to the theoretical band gap of silicon at absolute zero, 0K). This circuit concept was first published by David Hilbiber in 1964. Bob Widlar, Paul Brokaw and others followed up with other commercially successful versions. Operation The voltage difference between two p–n junctions (e.g. diodes), operated at different current densities, is used to generate a current that is ''proportional to absolute temperature'' (''PTAT'') in a 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 is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage Reference
A voltage reference is an electronic device that ideally produces a fixed (constant) voltage irrespective of the loading on the device, power supply variations, temperature changes, and the passage of time. Voltage references are used in power supplies, analog-to-digital converters, digital-to-analog converters, and other measurement and control systems. Voltage references vary widely in performance; a regulator for a computer power supply may only hold its value to within a few percent of the nominal value, whereas laboratory voltage standards have precisions and stability measured in parts per million. In metrology The earliest voltage references or standards were wet-chemical cells such as the Clark cell and Weston cell, which are still used in some laboratory and calibration applications. Laboratory-grade Zener diode secondary solid-state voltage standards used in metrology can be constructed with a drift of about 1 part per million per year.Manfred Kochsiek, Michael Gläser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parabola
In mathematics, a parabola is a plane curve which is mirror-symmetrical and is approximately U-shaped. It fits several superficially different mathematical descriptions, which can all be proved to define exactly the same curves. One description of a parabola involves a point (the focus) and a line (the directrix). The focus does not lie on the directrix. The parabola is the locus of points in that plane that are equidistant from both the directrix and the focus. Another description of a parabola is as a conic section, created from the intersection of a right circular conical surface and a plane parallel to another plane that is tangential to the conical surface. The line perpendicular to the directrix and passing through the focus (that is, the line that splits the parabola through the middle) is called the "axis of symmetry". The point where the parabola intersects its axis of symmetry is called the "vertex" and is the point where the parabola is most sharply curved. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicon Bandgap Temperature Sensor
The silicon bandgap temperature sensor is an extremely common form of temperature sensor (thermometer) used in electronic equipment. Its main advantage is that it can be included in a silicon integrated circuit at very low cost. The principle of the sensor is that the forward voltage of a silicon diode, which may be the base-emitter junction of a bipolar junction transistor (BJT), is temperature-dependent, according to the following equation: :V_=V_\left(1-\right)+V_\left(\frac\right)+ \left(\frac\right)\ln\left(\frac\right)+ \left(\frac\right)\ln\left(\frac\right) \, where :''T'' = temperature in kelvins, :''T''0 = reference temperature, :''V''''G''0 = bandgap voltage at absolute zero, :''V''''BE''0 = junction voltage at temperature ''T''0 and current ''I''C0, :''k'' = Boltzmann constant, :''q'' = charge on an electron, :''n'' = a device-dependent constant. By comparing the voltages of two junctions at the same temperature, but at two different currents, ''I''C1 and ''I'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LM317
The LM317 is a popular adjustable positive linear voltage regulator. It was designed by Bob Dobkin in 1976 while he worked at National Semiconductor. The LM337 is the negative complement to the LM317, which regulates voltages below a reference. It was designed by Bob Pease, who also worked for National Semiconductor. Specifications Without a heat sink with an ambient temperature at 50 °C such as on a hot summer day inside a box, a maximum power dissipation of (TJ-TA)/RθJA = ((125-50)/80) = 0.98 W can be permitted. (A piece of shiny sheet metal of aluminium with the dimensions 6 x 6 cm and 1.5 mm thick, results in a thermal resistance that permits 4.7 W of heat dissipation). In a constant voltage mode with an input voltage source at VIN at 34 V and a desired output voltage of 5 V, the maximum output current will be PMAX / (VI-VO) = 0.98 / (34-5) = 32 mA. For a constant current mode with an input voltage source at VIN at 12 V and a forward voltage drop of VF=3.6 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brokaw Bandgap Reference
Brokaw bandgap reference is a voltage reference circuit widely used in integrated circuits, with an output voltage around 1.25 V with low temperature dependence. This particular circuit is one type of a bandgap voltage reference, named after Paul Brokaw, the author of its first publication. Brokaw, P., "A simple three-terminal IC bandgap reference", ''IEEE Journal of Solid-State Circuits'', vol. 9, pp. 388–393, December 1974. Like all temperature-independent bandgap references, the circuit maintains an internal voltage source that has a positive temperature coefficient and another internal voltage source that has a negative temperature coefficient. By summing the two together, the temperature dependence can be canceled. Additionally, either of the two internal sources can be used as a temperature sensor. In the Brokaw bandgap reference, the circuit uses negative feedback (by means of an operational amplifier) to force a constant current through two bipolar transistors wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Dobkin
Robert C. Dobkin (born 1943 in Philadelphia) is an American electrical engineer, co-founder of Linear Technology Corporation, and veteran linear (analog) integrated circuit (IC) designer. Career Dobkin studied Electrical Engineering at MIT, but did not complete a degree. After early employments e.g. at GE Reentry Systems, he joined Philbrick Nexus in Massachusetts working on IC development with Bob Pease. He joined National Semiconductor (NSC) in January 1969. He resigned the position as Director of Advanced Circuit Development at NSC in July 1981 and co-founded Linear Technology with Robert H. Swanson in the same year. Dobkin continued to serve as the company's Chief Technical Officer through its acquisition by Analog Devices in 2016. He has been a Director of Spectra7 Microsystems Inc. since March 20, 2013. Dobkin holds more than 100 patents in the field of analog circuits. Works * LM118, first high speed operational amplifier. * LM199, heated buried-Zener voltage refer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TL431
The TL431 is a three-terminal adjustable precision shunt voltage regulator integrated circuit. With the use of an external voltage divider, a TL431 can regulate voltages ranging from 2.5 to 36 V, at currents up 100 mA. The typical initial deviation of reference voltage from the nominal 2.495 V level is measured in millivolts, the maximum worst-case deviation is measured in tens of millivolts. The circuit can control power transistors directly; combinations of the TL431 with power MOS transistors are used in high efficiency, very low dropout linear regulators. The TL431 is the ''de facto'' industry standard error amplifier circuit for switched-mode power supplies with optoelectronic coupling of the input and output networks. Texas Instruments introduced the TL431 in 1977. In the 21st century, the original TL431 remains in production along with a multitude of clones and derivatives (TL432, ATL431, KA431, LM431, TS431, 142ЕН19 and others). These functionally similar circuits may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Junction Transistor
A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor, uses only one kind of charge carrier. A bipolar transistor allows a small current injected at one of its terminals to control a much larger current flowing between the terminals, making the device capable of amplification or switching. BJTs use two p–n junctions between two semiconductor types, n-type and p-type, which are regions in a single crystal of material. The junctions can be made in several different ways, such as changing the doping of the semiconductor material as it is grown, by depositing metal pellets to form alloy junctions, or by such methods as diffusion of n-type and p-type doping substances into the crystal. The superior predictability and performance of junction transistors quickly displaced the original point-contact transistor. Diffused transistors, along wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noise (electronics)
In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects. In particular, noise is inherent in physics, and central to thermodynamics. Any conductor with electrical resistance will generate thermal noise inherently. The final elimination of thermal noise in electronics can only be achieved cryogenically, and even then quantum noise would remain inherent. Electronic noise is a common component of noise in signal processing. In communication systems, noise is an error or undesired random disturbance of a useful information signal in a communication channel. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources. Noise is, however, typically distinguished from interference, for example in the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR) and signal-to-noise plus interference ratio (SNIR) measu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Line Regulation
Line regulation is the ability of a power supply to maintain a constant output voltage despite changes to the input voltage, with the output current drawn from the power supply remaining constant. :\text = \frac \cdot 100\% where ΔVi is the change in input voltage while ΔVo is the corresponding change in output voltage. It is desirable for a power supply to maintain a stable output regardless of changes in the input voltage. The line regulation is important when the input voltage source is unstable or unregulated and this would result in significant variations in the output voltage. The line regulation for an unregulated power supply is usually very high for a majority of operations, but this can be improved by using a voltage regulator. A low line regulation is always preferred. In practice, a well regulated power supply should have a line regulation of at most 0.1%. In the regulator device datasheets the line regulation is expressed as percent change in output with respect to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operational Amplifier
An operational amplifier (often op amp or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op amp produces an output potential (relative to circuit ground) that is typically 100,000 times larger than the potential difference between its input terminals. The operational amplifier traces its origin and name to analog computers, where they were used to perform mathematical operations in linear, non-linear, and frequency-dependent circuits. The popularity of the op amp as a building block in analog circuits is due to its versatility. By using negative feedback, the characteristics of an op-amp circuit, its gain, input and output impedance, bandwidth etc. are determined by external components and have little dependence on temperature coefficients or engineering tolerance in the op amp itself. Op amps are used widely in electronic devices today, including a vast array of consumer, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field-effect Transistor
The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs control the flow of current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source. FETs are also known as unipolar transistors since they involve single-carrier-type operation. That is, FETs use either electrons (n-channel) or holes (p-channel) as charge carriers in their operation, but not both. Many different types of field effect transistors exist. Field effect transistors generally display very high input impedance at low frequencies. The most widely used field-effect transistor is the MOSFET (metal-oxide-semiconductor field-effect transistor). History The concept of a field-effect transistor (FET) was first patented by Austro-Hungarian physicist Julius Edgar Lilienfeld in 192 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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