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…

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…

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…

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…

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…

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…

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…

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…