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Widlar Current Mirror
] A Widlar current source is a modification of the basic two-transistor current mirror that incorporates an emitter degeneration resistor for only the output transistor, enabling the current source to generate low currents using only moderate resistor values. The Widlar circuit may be used with bipolar transistors, MOS transistors, and even vacuum tubes. An example application is the 741 operational amplifier, and Widlar used the circuit as a part in many designs.See, for example, Figure 2 i''IC voltage regulators'' This circuit is named after its inventor, Bob Widlar, and was patented in 1967.RJ Widlar: US Patent Number 03320439; Filed May 26, 1965; Granted May 16, 1967:Low-value current source for integrated circuits''/ref>See Widlar''Some circuit design techniques for linear integrated circuits''an''Design techniques for monolithic operational amplifiers''/ref> DC analysis Figure 1 is an example Widlar current source using bipolar transistors, where the emitter resistor R2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widlar Patent
Robert John Widlar (pronounced ''wide-lar''; November 30, 1937 – February 27, 1991) was an American electronics engineer and a designer of linear integrated circuits (ICs). Early years Widlar was born November 30, 1937 in Cleveland to parents of Czech, Irish and German ethnicity.Lojek, p. 250. His mother, Mary Vithous, was born in Cleveland to Czech immigrants Frank Vithous (František Vitous (or Vitouš?)) and Marie Zakova (Marie Žáková).Lojek, p. 249. His father, Walter J. Widlar, came from prominent German and Irish American families whose ancestors settled in Cleveland in the middle of the 19th century. A self-taught radio engineer, Walter Widlar worked for the radio station and designed pioneering ultra high frequency transmitters. The world of electronics surrounded him since birth: one of his brothers became the first baby monitored by wireless radio. Guided by his father, Bob developed a strong interest in electronics in early childhood. Widlar never talked ab ... [...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 gover ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog Circuits
Analogue electronics ( en-US, analog electronics) are electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two levels. The term "analogue" describes the proportional relationship between a signal and a voltage or current that represents the signal. The word analogue is derived from the el, word ανάλογος (analogos) meaning "proportional". Analogue signals An analogue signal uses some attribute of the medium to convey the signal's information. For example, an aneroid barometer uses the angular position of a needle as the signal to convey the information of changes in atmospheric pressure. Electrical signals may represent information by changing their voltage, current, frequency, or total charge. Information is converted from some other physical form (such as sound, light, temperature, pressure, position) to an electrical signal by a transducer which converts one type of energy into another (e.g. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilson Current Source
A Wilson current mirror is a three-terminal circuit (Fig. 1) that accepts an input current at the input terminal and provides a "mirrored" current source or sink output at the output terminal. The mirrored current is a precise copy of the input current. It may be used as a Wilson current source by applying a constant bias current to the input branch as in Fig. 2. The circuit is named after George R. Wilson, an integrated circuit design engineer who worked for Tektronix. Sedra, A.S. & K.C. Smith, Smith, K.C.: "Microelectronic Circuits, 6th Ed.", OUP (2010), pp. 539 - 541. Wilson devised this configuration in 1967 when he and Barrie Gilbert challenged each other to find an improved current mirror overnight that would use only three transistors. Wilson won the challenge.Gilbert, B., "Bipolar Current Mirrors," in "Analogue IC Design: the Current-Mode Approach," Eds. Toumazou, C., Lidgey, F. J. & Haigh, D. G., Peter Peregrinus Ltd. (1990), , pp. 268-275. Circuit operation There are t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current Source
A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it. A current source is the dual of a voltage source. The term ''current sink'' is sometimes used for sources fed from a negative voltage supply. Figure 1 shows the schematic symbol for an ideal current source driving a resistive load. There are two types. An ''independent current source'' (or sink) delivers a constant current. A ''dependent current source'' delivers a current which is proportional to some other voltage or current in the circuit. Background , - align="center" , style="padding: 1em 2em 0;", , style="padding: 1em 2em 0;", , - align="center" , Voltage source , Current source , - align="center" , style="padding: 1em 2em 0;", , style="padding: 1em 2em 0;", , - align="center" , Controlled voltage source , Controlled current source , - align="center" , style="padding: 1em 2em 0;", , style="padding: 1em 2em 0;", , - align ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widlar Resistance Plot
Robert John Widlar (pronounced ''wide-lar''; November 30, 1937 – February 27, 1991) was an American electronics engineer and a designer of linear integrated circuits (ICs). Early years Widlar was born November 30, 1937 in Cleveland to parents of Czech, Irish and German ethnicity.Lojek, p. 250. His mother, Mary Vithous, was born in Cleveland to Czech immigrants Frank Vithous (František Vitous (or Vitouš?)) and Marie Zakova (Marie Žáková).Lojek, p. 249. His father, Walter J. Widlar, came from prominent German and Irish American families whose ancestors settled in Cleveland in the middle of the 19th century. A self-taught radio engineer, Walter Widlar worked for the radio station and designed pioneering ultra high frequency transmitters. The world of electronics surrounded him since birth: one of his brothers became the first baby monitored by wireless radio. Guided by his father, Bob developed a strong interest in electronics in early childhood. Widlar never talked ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Current Dependence Of Output Resistance
Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (stream), currents in rivers and streams ** Convection current, flow caused by unstable density variation due to temperature differences * Current (mathematics), geometrical current in differential topology * Conserved current, a field associated to a symmetry in field theory * Electric current, a flow of electric charge through a medium * Probability current, in quantum mechanics * IBM Current, an early personal information management program Arts and entertainment Music * ''Current'' (album), a 1982 album by Heatwave * ''Currents'' (Eisley album) * ''Currents'' (Tame Impala album) * "The Current" (song), by the Blue Man Group * "Currents", a song by Dashboard Confessional from ''Dusk and Summer'', 2006 * "Currents", a song by Drake from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 A two-port network (a kind of four-terminal network or quadripole) is an electrical network ( circuit) or device with two ''pairs'' of terminals to connect to external circuits. Two terminals constitute a port if the currents applied to them sati ... 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_\te ... [...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 circuit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Widlar Small-signal
Robert John Widlar (pronounced ''wide-lar''; November 30, 1937 – February 27, 1991) was an American electronics engineer and a designer of linear integrated circuits (ICs). Early years Widlar was born November 30, 1937 in Cleveland to parents of Czech, Irish and German ethnicity.Lojek, p. 250. His mother, Mary Vithous, was born in Cleveland to Czech immigrants Frank Vithous (František Vitous (or Vitouš?)) and Marie Zakova (Marie Žáková).Lojek, p. 249. His father, Walter J. Widlar, came from prominent German and Irish American families whose ancestors settled in Cleveland in the middle of the 19th century. A self-taught radio engineer, Walter Widlar worked for the radio station and designed pioneering ultra high frequency transmitters. The world of electronics surrounded him since birth: one of his brothers became the first baby monitored by wireless radio. Guided by his father, Bob developed a strong interest in electronics in early childhood. Widlar never talked ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambert W Function
In mathematics, the Lambert function, also called the omega function or product logarithm, is a multivalued function, namely the Branch point, branches of the converse relation of the function , where is any complex number and is the exponential function. For each integer there is one branch, denoted by , which is a complex-valued function of one complex argument. is known as the principal branch. These functions have the following property: if and are any complex numbers, then :w e^ = z holds if and only if :w=W_k(z) \ \ \text k. When dealing with real numbers only, the two branches and suffice: for real numbers and the equation :y e^ = x can be solved for only if ; we get if and the two values and if . The Lambert relation cannot be expressed in terms of elementary functions. It is useful in combinatorics, for instance, in the enumeration of tree graph, trees. It can be used to solve various equations involving exponentials (e.g. the maxima of the Planck' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcendental Equation
In applied mathematics, a transcendental equation is an equation over the real number, real (or complex number, complex) numbers that is not algebraic equation, algebraic, that is, if at least one of its sides describes a transcendental function. Examples include: :\begin x &= e^ \\ x &= \cos x \\ 2^x &= x^2 \end A transcendental equation need not be an equation between elementary functions, although most published examples are. In some cases, a transcendental equation can be solved by transforming it into an equivalent algebraic equation. Some such transformations are sketched #Transformation into an algebraic equation, below; computer algebra systems may provide more elaborated transformations. In general, however, only approximate solutions can be found. Transformation into an algebraic equation Ad hoc methods exist for some classes of transcendental equations in one variable to transform them into algebraic equations which then might be solved. Exponential equations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
