 |
Hybrid-pi Model
The hybrid-pi model is a popular circuit model used for analyzing the small signal behavior of bipolar junction and field effect transistors. Sometimes it is also called Giacoletto model because it was introduced by L.J. Giacoletto in 1969. The model can be quite accurate for low-frequency circuits and can easily be adapted for higher frequency circuits with the addition of appropriate inter-electrode capacitances and other parasitic elements. BJT parameters The hybrid-pi model is a linearized two-port network approximation to the BJT using the small-signal base-emitter voltage, \scriptstyle v_\text, and collector-emitter voltage, \scriptstyle v_\text, as independent variables, and the small-signal base current, \scriptstyle i_\text, and collector current, \scriptstyle i_\text, as dependent variables. A basic, low-frequency hybrid-pi model for the bipolar transistor is shown in figure 1. The various parameters are as follows. :g_\text = \left.\frac\right\vert_ = \frac is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
 |
Electronic Circuit
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. It is a type of electrical circuit and to be referred to as ''electronic'', rather than ''electrical'', generally at least one active component must be present. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another. Circuits can be constructed of discrete components connected by individual pieces of wire, but today it is much more common to create interconnections by photolithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit. In an integrated circuit or IC, the components and interconnections are forme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
 |
Kelvin
The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907). The Kelvin scale is an absolute thermodynamic temperature scale, meaning it uses absolute zero as its null (zero) point. Historically, the Kelvin scale was developed by shifting the starting point of the much-older Celsius scale down from the melting point of water to absolute zero, and its increments still closely approximate the historic definition of a degree Celsius, but since 2019 the scale has been defined by fixing the Boltzmann constant to be exactly . Hence, one kelvin is equal to a change in the thermodynamic temperature that results in a change of thermal energy by . The temperature in degree Celsius is now defined as the temperature in kelvins minus 273.15, meanin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
65 Nanometer
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. 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. Toshiba and Sony announced the 65 nm process in 2002, before Fujitsu and Toshiba began production in 2004, and then TSMC began production in 2005. 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 corr ... [...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] |
 |
Threshold Voltage
The threshold voltage, commonly abbreviated as Vth or VGS(th), of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals. It is an important scaling factor to maintain power efficiency. When referring to a junction field-effect transistor (JFET), the threshold voltage is often called pinch-off voltage instead. This is somewhat confusing since ''pinch off'' applied to insulated-gate field-effect transistor (IGFET) refers to the channel pinching that leads to current saturation behaviour under high source–drain bias, even though the current is never off. Unlike ''pinch off'', the term ''threshold voltage'' is unambiguous and refers to the same concept in any field-effect transistor. Basic principles In n-channel ''enhancement-mode'' devices, a conductive channel does not exist naturally within the transistor, and a positive gate-to-source voltage is necessary to create one ... [...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 active device in an amplifier. 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 which 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 or vacuum tube in a circ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
 |
MOSFET
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. A metal-insulator-semiconductor field-effect transistor (MISFET) is a term almost synonymous with MOSFET. Another synonym is IGFET for insulated-gate field-effect transistor. The basic principle of the field-effect transistor was first patented by Julius Edgar Lilienfeld in 1925.Lilienfeld, Julius Edgar (1926-10-08) "Method and apparatus for controlling electric currents" upright=1.6, Two power MOSFETs in watt.html" ;"title="amperes">A in the ''on'' state, dissipating up to about 100 watt">W and controlling a load of over 2000 W. A matchstick is pictured ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
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, ''g''m, with a subscript, m, for ''mutual''. It is defined as follows: :g_m = \frac For small signal alternating current, the definition is simpler: :g_m = \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 notated as ''r''m: :r_m = \fr ... [...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 than i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
|
Early Effect
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 base is more heavily doped than the collector. The principle gov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |