Manual 18492469
*5.28 Augment the model of the npn BJT shown in Fig. 5.20(a)
by a current source representing Ig. Assume that r, is very
large and thus can be neglected. In terms of this addition,
what do the terminal currents iy, i, and i; become? If the
base lead is open-circuited while the emitter is connected to
ground and the collector is connected to a positive supply,
tind the emitter and collector currents.
D5.56 Consider the CE amplifier circuit of Fig. 5.26(a)
when operated with a dc supply Vc =+5 V. It is required to
find the point at which the transistor should be biased; that
is, find the value of Vc; so that the output sine-wave signal
vu, resulting from an input sine-wave signal v,, of 5-mV
peak amplitude has the maximum possible magnitude. What
is the peak amplitude of the output sine wave and the value
of the gain obtained? Assume linear operation around the
bias point. (Hint: To obtain the maximum possible output
amplitude for a given input, you need to bias the. transistor
as close to the edge of saturation as possible without enter-
ing saturation at any time, that is, without vc; decreasing
below 0.3 V.) |
5 ‚63 Consider the characteristic curves shown in Fig 5.29
with the following additional calibration data: Label fr
the lowest colored line, ig = 1 uA, 10 HA, 20 ДА 30 А nd
40 HA. Assume the lines to be horizontal, and let = 100
Рог Усс = 5 У апа Rc = 1 kQ, what peak-to-peak collector
voltage swing will result for ‘в varying over the range 10 uA
© 40 uA? If, at a new bias point (not the one shown in the
Igure) Ver = 3 Ve, find the value of Ic and I. If at th
5 С в. Па! {11$ cur-
rent Var = 0.7 у and if Ry =
of Vos.
100 kQ, find the required value
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