reffec.com

pN > in .NET Encoding ANSI/AIM Code 128 in .NET pN >

7. use .net framework barcode 128 creator toassign code128 on .net Microsoft Office Official Website the transistor s .NET ANSI/AIM Code 128 tructure. With these definitions, the normal components of current become , QN ICN = > IEN = + ".

,n no . (7-38a). Similarly, the i visual .net Code 128 Code Set B nverted components are / / = ~ , la =-^--^(7-38b). where the / subs cripts on the stored charge and on the transit and recombination times designate the inverted mode. Combining these equations as in Eq. (7-32) we have the terminal currents for general biasing: h = QH(~T.

V~)-V-. (7-398). k = f1 - e,(f + f ). (7-3*). It is not diffic code-128c for .NET ult to show that these equations correspond to the Ebers-Moll relations [Eq. (7-34)], where.

pN > Tpl i ~ ot-N tN + TpN tl + hs = qN{~-. + -r-\. /^ = 9/(^ + ^-). (7-40). The base current .net framework Code 128 Code Set A in the normal mode supports recombination, and the base-to-collector current amplification factor $N takes the form predicted byEq.(7-7):.

j - On. a _ kit - IfE *BN ~ TpN PN ~ r - ~ J J-BN tN (./-41). This expression Code 128 Code Set A for .NET for $N is also obtained from aA,/(l - aN). Similarly, IB/ is Qihph and the total base current is h = hN+ 181 = ^ + 1 VV Tpl.

QN QI (7-42). This expression for the base current is substantiated by IE - Ic from Eq. (7-39). The effects of time dependence of stored charge can be included in these equations by the methods introduced in Section 5.

5.1. We can include.

Bipolar Junction Transistors the proper depen dencies by adding a rate of change of stored charge to each of the injection currents IEN and ICI:. \T/Ar T PN/. ic = . tB-. Q*_ Q(JL + ) _. QN ^QI (7_43b). , dQN dQl + + + (7-43c) 7 tpi dt dt PN We shall return to these equations in Section 7.8, when we discuss the use of transistors at high frequencies. In a switching operation a transistor is usually controlled in two conduction 7.

6 states, which can be referred to loosely as the "on" state and the "off" state. SWITCHING Ideally, a switch should appear as a short circuit when turned on and an open circuit when turned off. Furthermore, it is desirable to switch the device from one state to the other with no lost time in between.

Transistors do not fit this ideal description of a switch, but they can serve as a useful approximation in practical electronic circuits. The two states of a transistor in switching can be seen in the simple common-emitter example of Fig. 7-12.

In this figure the collector current ic is controlled by the base current iB over most of the family of characteristic curves. The load line specifies the locus of allowable (to - VCE) points for the circuit, in analogy with Fig. 6-2.

If iB is such that the operating point lies somewhere between the two end points of the load line (Fig. 7-12b), the transistor operates in the normal active mode. That is, the emitter junction is forward biased and the collector is reverse biased, with a reasonable value of iB flowing out of the base.

On the other hand, if the base current is zero or negative, the point C is reached at the bottom end of the load line, and the collector current is negligible. This is the "off" state of the transistor, and the device is said to be operating in the cutoff regime. If the base current is positive and sufficiently large, the device is driven to the saturation regime, marked S.

This is the "on" state of the transistor, in which a large value of ic flows with only a very small voltage drop vCE. As we shall see below, the beginning of the saturation regime corresponds to the loss of reverse bias across the collector junction. In a typical switching operation the base current swings from positive to negative, thereby driving the device from saturation to cutoff, and vice versa.

In this section we shall explore the nature of conduction in the cutoff and saturation regimes; also we shall investigate the factors affecting the speed with which the transistor can be switched between the two states. The various regions of operation of a BJT are illustrated in Fig. 7-12c.

If the emitter junction is forward biased and the collector reverse biased,.
Copyright © reffec.com . All rights reserved.