Category Archive for: Bias Design in Discrete and Integrated Circuits

SMALL-SIGNAL PERFORMANCE OF THE BIAS-STABILIZED CIRCUIT

Figure 6-t a) shows the bias-stabilized circuit incorporated into an ac amplifier stage. Both source resistance and load resistance are included. Figure 6-6(b) shows the ac equivalent circuit. of the amplifier. Note that RI and R1 are both connected to ac ground and are therefore in parallel as far as ac signals are concerned. These…

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BIAS DESIGN IN DISCRETE INTEGRATED CIRCUITS

THE EFFECTS OF PARAMETER VARIABILITY We have seen the values of transistor parameters cannot be treated as a ‘I’ constant. since til eye change with b n temperature and bias conditions. COL’ ” changes in parameter values can change the bias point of a transistor. The pat,.ear fr is a prime example: it increases with…

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STABILITY FACTORS

The ratio of a change in collector current to the change in the parameter value that caused  it is called a stability factor, A stability factor is thus a measure of how sensitive collector bias current is to changes ill a parameter value. Stability factors can be defined for each of the three parameter,s we…

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CALCULATING THE BIAS POINT OF THE STABILIZED CIRCUIT

If the stabilized bias design in Figure 6-1 truly makes the bias point independent of parameter values, then it should be possible to determine the quiescent current and voltage without using any parameter values in the computations. The analysis procedure that follows will demonstrate that this is indeed the case. Refer to Figure 6-4. Note…

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Bias and small-signal equations for the”

emitter-stabilized CE amplifier Rill = (,B + l)RE,BR£ (~) VB  Rt + Merrill Vc (Rt ~2 R 2 ) Vcc (Rill » R2) V =< VB – 0.7 (Si) I R£ ( ; (Rt ~2 R) Vcc – VBE) Ic = {J Rd l R2 + ({J + l)RE Vc = Vcc – IeRc – feRE…

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STABILIZATION BY COLLECTOR FEEDBACK

Figure 6-10 shows another bias design that is sometimes used to stabilize a CE amplifier against parameter changes. Note that the resistor IS connected between collector and base and thus provides a feedback path between output and input. For this reason, the design is called collector feedback or voltage feedback. The figure also shows an…

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DISCRETE CIRCllIT BIAS DESIGN

Because the voltage-divider bias circuit (Figure 6-11) has been so widely used. certain practical, time-tested guidelines have evolved for its design. It has been found that reasonable compromises between stability, gain, and output swing can  be achieved by designing the bias circuit in accordance with two basic criteria. First the emitter-to-ground voltage should be approximately…

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INTEGRATED CIRCUITS

The methods used to bias amplifiers in integrated circuits are substantially different from those used in discrete circuits. To understand why this is the case and to appreciate the constraints imposed by integrated circuit technology on circuit design in general, it is necessary to learn some fundamental facts about how integrated circuits are constructed. Applications…

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PN Device Fabrication-The Photolithographic Process

The method most widely used for integrated-circuit fabrication is now also used to produce discrete devices. The process to which we refer, called batch production using photo lithographic methods, is a truly remarkable blend of ingenuity and precision, and is responsible for many dramatic achievements in the lido of micro-miniature electronics. The manufacturing procedure is…

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PN junctions in an N-typc crystal

illustrates how the steps we have described so far could be used to create two PN junctions in an N-typc crystal. The final steps in the photo lithographic processing are those required to deposit metal contact surfaces where terminal leads can be attached and. in the case of integrated circuits, any metallic paths needed to…

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