Skip to main content
Engineering LibreTexts

7.8: Exercises

  • Page ID
    34248
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

    ( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\id}{\mathrm{id}}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\kernel}{\mathrm{null}\,}\)

    \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\)

    \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\)

    \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    \( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

    \( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

    \( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vectorC}[1]{\textbf{#1}} \)

    \( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

    \( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

    \( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)

    Unless otherwise specified, use \(\beta = 100\).

    7.8.1: Analysis Problems

    1. Determine the input and output impedances of the circuit of Figure \(\PageIndex{1}\).

    clipboard_e7489ccdcf6b0efe42b190896afb665b3.png

    Figure \(\PageIndex{1}\)

    2. Determine the load voltage for the circuit of Figure \(\PageIndex{1}\) if \(V_{in}\) is 10 mV.

    3. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{2}\) if \(V_{in}\) is 70 mV.

    clipboard_e08588dc0e090b2342d0ffe58a9f7baa2.png

    Figure \(\PageIndex{2}\)

    4. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{3}\) if \(V_{in}\) is 50 mV.

    clipboard_e51c9323826cce7a14130334666402415.png

    Figure \(\PageIndex{3}\)

    5. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{4}\) if \(V_{in}\) is 25 mV.

    clipboard_e9e202383fda15823bf1ddd3bf4fe602a.png

    Figure \(\PageIndex{4}\)

    6. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{5}\) if \(V_{in}\) is 30 mV.

    clipboard_e2a6c1e1e02b4436a2b70c6360c334196.png

    Figure \(\PageIndex{5}\)

    7. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{6}\) if \(V_{in}\) is 60 mV.

    clipboard_e6613c7a912210166ce239756e1e951c2.png

    Figure \(\PageIndex{6}\)

    8. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{7}\) if \(V_{in}\) is 150 mV.

    clipboard_eb7ad222c231eba07dfec459e0605f537.png

    Figure \(\PageIndex{7}\)

    9. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{8}\) if \(V_{in}\) is 200 mV.

    clipboard_e1169e9a4f86b8186186067abb37c1ce9.png

    Figure \(\PageIndex{8}\)

    10. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{9}\) if \(V_{in}\) is 250 mV.

    clipboard_e2fc3a3c502ed91a31491a8b0b0029f0d.png

    Figure \(\PageIndex{9}\)

    11. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{10}\) if \(V_{in}\) is 300 mV.

    clipboard_e8102f479db8e298f01d007abfbe87d0c.png

    Figure \(\PageIndex{10}\)

    12. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{11}\) if \(V_{in}\) is 50 mV.

    clipboard_e3ded4d5b71ed948841db1771ef358504.png

    Figure \(\PageIndex{11}\)

    13. Determine \(Z_{in}\), \(Z_{out}\), and the load voltage for the circuit of Figure \(\PageIndex{12}\) if \(V_{in}\) is 2 mV.

    clipboard_e7f0a6db84e8ead161829853df718f271.png

    Figure \(\PageIndex{12}\)

    7.8.2: Design Problems

    14. Redesign the circuit of Figure \(\PageIndex{2}\) to halve the existing gain while keeping the Q point where it is currently.

    15. By using a Darlington pair, redesign the circuit of Figure \(\PageIndex{3}\) to double \(Z_{in}\).

    16. Redesign the circuit of Figure \(\PageIndex{3}\) so that it exhibits the same performance parameters but uses a PNP device.

    17. Redesign the circuit of Figure \(\PageIndex{5}\) to double the existing gain while keeping the Q point where it is currently.

    18. Redesign the circuit of Figure \(\PageIndex{7}\) so that it exhibits the same performance parameters but uses an NPN device.

    7.8.3: Challenge Problems

    19. Determine the gain and input impedance for the circuit of Figure \(\PageIndex{13}\). \(V_{CC}\) = 20 V, \(V_{EE}\) = −10 V, \(R_B\) = 18 k\(\Omega\), \(R_{E1}\)= 10 k\(\Omega\), \(R_{C1}\) = 12 k\(\Omega\), \(R_1\) = 33 k\(\Omega\), \(R_2\) = 15 k\(\Omega\), \(R_{E2}\) = 5.6 k\(\Omega\), \(R_{SW}\) = 400 k\(\Omega\), \(R_{C2}\) = 6.8 k\(\Omega\), \(R_L\) = 24 k\(\Omega\).

    clipboard_e37c63a9f3e31c5ce006eb66d5141777e.png

    Figure \(\PageIndex{13}\)

    20. For the circuit of Figure \(\PageIndex{10}\), replace its load resistor with the circuit of Figure \(\PageIndex{6}\) and determine the combined gain and input impedance of the system.

    7.8.4: Computer Simulation Problems

    21. Use a transient analysis to verify the load voltage of problem 3.

    22. Use a transient analysis to verify the load voltage of problem 4.

    23. Use a transient analysis to verify the load voltage of problem 8.

    24. Consider the amplifier of Figure \(\PageIndex{1}\). Replace the 4.3 k\(\Omega\) emitter resistor with a potentiometer of the same value. Connect the wiper arm to the emitter bypass capacitor. Run several transient analyses at different pot settings (0%, 25%, 50%, etc.). What can you conclude from the results?


    This page titled 7.8: Exercises is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by James M. Fiore via source content that was edited to the style and standards of the LibreTexts platform.

    • Was this article helpful?