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Transresistance
Transconductance (for transfer conductance), also infrequently called mutual conductance, is the electrical characteristic relating the current through the output of a device to the voltage across the input of a device. Conductance is the reciprocal of resistance. Transadmittance (or transfer admittance) is the AC equivalent of transconductance. Definition Transconductance is very often denoted as a conductance, , with a subscript, , for ''mutual''. It is defined as follows: : g_\text = \frac For small signal alternating current, the definition is simpler: : g_\text = \frac The SI unit for transconductance is the siemens, with the symbol S, as in conductance. Transresistance Transresistance (for transfer resistance), also infrequently referred to as mutual resistance, is the dual of transconductance. It refers to the ratio between a change of the voltage at two output points and a related change of current through two input points, and is denotated as : : r_\text = \ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Conductance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with mechanical friction. The SI unit of electrical resistance is the ohm (), while electrical conductance is measured in siemens (S) (formerly called the 'mho' and then represented by ). The resistance of an object depends in large part on the material it is made of. Objects made of electrical insulators like rubber tend to have very high resistance and low conductance, while objects made of electrical conductors like metals tend to have very low resistance and high conductance. This relationship is quantified by resistivity or conductivity. The nature of a material is not the only factor in resistance and conductance, however; it also depends on the size and shape of an object because these properties are extensive rather tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel Length Modulation
Channel length modulation (CLM) is an effect in field effect transistors, a shortening of the length of the inverted channel region with increase in drain bias for large drain biases. The result of CLM is an increase in current with drain bias and a reduction of output resistance. It is one of several short-channel effects in MOSFET scaling. It also causes distortion in JFET amplifiers. To understand the effect, first the notion of pinch-off of the channel is introduced. The channel is formed by attraction of carriers to the gate, and the current drawn through the channel is nearly a constant independent of drain voltage in saturation mode. However, near the drain, the gate ''and drain'' jointly determine the electric field pattern. Instead of flowing in a channel, beyond the pinch-off point the carriers flow in a subsurface pattern made possible because the drain and the gate both control the current. In the figure at the right, the channel is indicated by a dashed line and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operational Transconductance Amplifier
The operational transconductance amplifier (OTA) is an amplifier that outputs a Electric current, current proportional to its input voltage. Thus, it is a voltage controlled current source. Three types of OTAs are single-input single-output, differential-input single-output, and differential-input differential-output (a.k.a. fully differential), however this article focuses on differential-input single-output. There may be an additional input for a current to control the amplifier's transconductance. The first commercially available integrated circuit units were produced by RCA in 1969 (before being acquired by General Electric) in the form of the CA3080. Although most units are constructed with bipolar transistors, field effect transistor units are also produced. Like a standard operational amplifier, the OTA also has a high Electrical impedance, impedance differential input stage and may be used with negative feedback. But the OTA differs in that: * The OTA outputs a ''curre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-power Bandwidth
The half-power point is the condition at which a system's output power has dropped to half of its peak value; that is, at a level of approximately . In filters, optical filters, and electronic amplifiers, the half-power point is also known as half-power bandwidth and is a commonly used definition for the cutoff frequency. In the characterization of antennas the half-power point is also known as half-power beamwidth and relates to measurement position as an angle and describes directionality. Amplifiers and filters This occurs when the output voltage has dropped to \tfrac \approx \text of the filter's nominal passband voltage and the power has dropped by half. A bandpass amplifier will have two half-power points, while a low-pass amplifier or a high-pass amplifier will have only one. The bandwidth of a filter or amplifier is usually defined as the difference between the lower and upper half-power points. This is, therefore, also known as the bandwidth. There is no lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cascode
The cascode is a two-stage amplifier that consists of a common emitter stage feeding into a common base stage when using bipolar junction transistors (BJTs) or alternatively a common source stage feeding a common gate stage when using field-effect transistors (FETs). Because there is no direct coupling from the output to input, the Miller effect is eliminated, contributing to a much higher bandwidth. Compared to a single amplifier stage, this combination may have one or more of the following characteristics: higher input–output isolation, higher input impedance, high output impedance, higher bandwidth (signal processing), bandwidth. History The use of a cascode (sometimes verbification, verbified to ''cascoding'') is a common technique for improving analog circuit performance, applicable to both vacuum tubes and transistors. The name "cascode" was coined in an article written by Frederick Vinton Hunt and Roger Wayne Hickman in 1939, in a discussion on the application of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Network Analysis (electrical Circuits)
In electrical engineering and electronics, a '' network'' is a collection of interconnected components. Network analysis is the process of finding the voltages across, and the currents through, all network components. There are many techniques for calculating these values; however, for the most part, the techniques assume linear components. Except where stated, the methods described in this article are applicable only to ''linear'' network analysis. Definitions Equivalent circuits A useful procedure in network analysis is to simplify the network by reducing the number of components. This can be done by replacing physical components with other notional components that have the same effect. A particular technique might directly reduce the number of components, for instance by combining impedances in series. On the other hand, it might merely change the form into one in which the components can be reduced in a later operation. For instance, one might transform a voltage ge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Voltage
The Early effect, named after its discoverer James M. Early, is the variation in the effective width of the base in a bipolar junction transistor (BJT) due to a variation in the applied base-to-collector voltage. A greater reverse bias across the collector–base junction, for example, increases the collector–base depletion width, thereby decreasing the width of the charge carrier portion of the base. Explanation In Figure 1, the neutral (i.e. active) base is green, and the depleted base regions are hashed light green. The neutral emitter and collector regions are dark blue and the depleted regions hashed light blue. Under increased collector–base reverse bias, the lower panel of Figure 1 shows a widening of the depletion region in the base and the associated narrowing of the neutral base region. The collector depletion region also increases under reverse bias, more than does that of the base, because the collector is less heavily doped than the base. The principle gove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha (%CE%B1) And Beta (%CE%B2)
Alpha (uppercase , lowercase ) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter ''aleph'' , whose name comes from the West Semitic word for ' ox'. Letters that arose from alpha include the Latin letter and the Cyrillic letter . Uses Greek In Ancient Greek, alpha was pronounced and could be either phonemically long ( ː or short ( . Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today: . * = ' "a time" * = ' "tongue" In Modern Greek, vowel length has been lost, and all instances of alpha simply represent the open front unrounded vowel . In the polytonic orthography of Greek, alpha, like other vowel letters, can occur with several diacritic marks: any of three accent symbols (), and either of two breathing marks (), as well as combinations of these. It can also combine with the iota subscript (). Greek grammar In the Attic� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boltzmann Constant
The Boltzmann constant ( or ) is the proportionality factor that relates the average relative thermal energy of particles in a ideal gas, gas with the thermodynamic temperature of the gas. It occurs in the definitions of the kelvin (K) and the molar gas constant, in Planck's law of black-body radiation and Boltzmann's entropy formula, and is used in calculating Johnson–Nyquist noise, thermal noise in resistors. The Boltzmann constant has Dimensional analysis, dimensions of energy divided by temperature, the same as entropy and heat capacity. It is named after the Austrian scientist Ludwig Boltzmann. As part of the 2019 revision of the SI, the Boltzmann constant is one of the seven "Physical constant, defining constants" that have been defined so as to have exact finite decimal values in SI units. They are used in various combinations to define the seven SI base units. The Boltzmann constant is defined to be exactly joules per kelvin, with the effect of defining the SI unit ke ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Q-point
In electronics, biasing is the setting of DC (direct current) operating conditions (current and voltage) of an electronic component that processes time-varying signals. Many electronic devices, such as diodes, transistors and vacuum tubes, whose function is processing time-varying ( AC) signals, also require a steady (DC) current or voltage at their terminals to operate correctly. This current or voltage is called ''bias''. The AC signal applied to them is superposed on this DC bias current or voltage. The operating point of a device, also known as bias point, quiescent point, or Q-point, is the DC voltage or current at a specified terminal of an active device (a transistor or vacuum tube) with no input signal applied. A bias circuit is a portion of the device's circuit that supplies this steady current or voltage. Overview In electronics, 'biasing' usually refers to a fixed DC voltage or current applied to a terminal of an electronic component such as a diode, transistor ... [...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 (FET), 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 between the remaining two 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 trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
65 nm Process
The 65 nm process is an advanced lithographic node used in volume CMOS (MOSFET) semiconductor fabrication. Printed linewidths (i.e. transistor gate lengths) can reach as low as 25 nm on a nominally 65 nm process, while the pitch between two lines may be greater than 130 nm. Process node For comparison, cellular ribosomes are about 20 nm end-to-end. A crystal of bulk silicon has a lattice constant of 0.543 nm, so such transistors are on the order of 100 atoms across. By September 2007, Intel, AMD, IBM, UMC and Chartered were also producing 65 nm chips. While feature sizes may be drawn as 65 nm or less, the wavelengths of light used for lithography are 193 nm and 248 nm. Fabrication of sub-wavelength features requires special imaging technologies, such as optical proximity correction and phase-shifting masks. The cost of these techniques adds substantially to the cost of manufacturing sub-wavelength semiconductor products, with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
