*10.48 It is required to show that the output resistance of the BJT circuit in Fig. P10.48 is given by R,= r, +[R,|| (*,,+ R,)]1+gm". + Ry To derive this expression, set V= 0, replace the BJT with its small-signal, hybrid-T model, apply a test voltage V, to the collector, and find the current I, drawn from V and hence R, as V,/I.. Note that the bias arrangement is not shown. For the case of R, = 0, find the maximum possible value for R: Note that this theoretical maximum is obtained when R. is so large that the signal current in the emitter is nearly zero. In this case, with V applied and 0, what is the current in the base, in the gmVn genera- S X. Vs tor, and in r, , all in terms of I, ? Show these currents on a sketch of the equivalent circuit with R, set to o.
Power Amplifier
The power amplifier is an electronic amplifier designed to maximize the signal strength of a given input. The input signal strength is enhanced to a high enough level to drive output devices such as speakers, headphones, RF (Radio frequency) transmitters, etc. Unlike voltage / current amplifiers, the power amplifier is designed to drive core loads directly and is used as a storage block in the amplifier series.
Maximum Efficiency Criterion
In every field of engineering, there is a tremendous use of the machine and all those machines are equipped for their popular work efficiency so it very much important for operation engineers to monitor the efficiency of the machine, planning engineers to check out the efficiency of the machine before installing the machine and design engineers to design machine for higher efficiency than and then the utility will procure their products that will ultimately lead to profit and loss of the company. It indicates the importance of efficiency right from the initial stage as manufacturing units, intermediate stage as planning coordinators, and end-users stage as a utility.
![*10.48 It is required to show that the output resistance of
the BJT circuit in Fig. P10.48 is given by
R,= r, + [R_ || (rx + R,)] (1+
1 +gmr.
+ RB
To derive this expression, set V= 0, replace the BJT with
its small-signal, hybrid-T model, apply a test voltage V to
the collector, and find the current I, drawn from V, and
hence R, as V,/I.. Note that the bias arrangement is not
shown. For the case of R,
S
0, find the maximum possible
value for R,. Note that this theoretical maximum is
obtained when R, is so large that the signal current in the
emitter is nearly zero. In this case, with V, applied and
V. = 0, what is the current in the base, in the g„V7 genera-
tor, and in re, all in terms of I, ? Show these currents on a
sketch of the equivalent circuit with R, set to ∞.
R,
R.
V.
Re
Figure P10.48](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fef05fe35-d967-4193-8ca3-132c74c43a38%2F02e14b79-f8ed-45eb-9bde-cd43c16462e6%2F9pes3r_processed.jpeg&w=3840&q=75)
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