Log out Go to App
Go to App

Learning Materials

Features

Discover

Chapter 5: Problem 66

a. Given \(\beta=120, r_{e}=4.5 \Omega\), and \(r_{o}=40 \mathrm{k} \Omega\), sketch the approximate hybrid equivalent circuit. b. Given \(h_{i e}=1 \mathrm{k} \Omega, h_{r e}=2 \times 10^{-4}, h_{f e}=90\), and \(h_{o e}=20 \mu \mathrm{S}\), sketch the \(r_{e}\) model.

Short Answer

Expert verified
Two sketches are created, each one for different model. First one is the hybrid equivalent circuit with three elements: \(r_{e}=4.5 \Omega\), \(r_{o}=40 k\Omega\) and \( βI_{b} = 120l_{b}\). Second is the re model with four elements: \( h_{ie}=1 k\Omega \),\( h_{fe}I_{b}=90I_{b} \),\( h_{re}V_{ce}=2*10^{-4}V_{ce}\) and \( h_{oe}V_{ce}=20 \mu S* V_{ce}\).

Step by step solution

01

Sketch the Hybrid Equivalent Circuit

Start by drawing a simple three-node circuit with two inputs and one output. Mark the nodes as e (emitter), b(base) and c(collector). Connect a resistor representing external emitter resistance \(r_{e}=4.5 \Omega\) from e to ground. Add a resistance to the c terminal representing the output resistance \(r_{o}=40 k\Omega\) from c to ground.The current controlled current source \( βI_{b} \) which is \(120l_{b}\) is connected between c and e terminal. The control signal \(I_{b}\) enters through the input port b-e.
02

Sketch the re model

The re model, also known as simplified hybrid model, use different parameters.Draw a three node circuit with two inputs and one output. The input resistance \( h_{ie}=1 k\Omega \) is between b and e terminal from base to ground.The transconductance component is the current controlled current source \(h_{fe}I_{b}=90I_{b}\) from c to e. Another resistor \(h_{re}V_{ce}=2*10^{-4}V_{ce}\) is in parallel with the controlled current source \(h_{fe}I_{b}=90I_{b}\), this is a voltage controlled current source from c to e.The output admittance is \(h_{oe}V_{ce}=20 \mu S * V_{ce}\) that is connected across the c terminal to the ground. This is a voltage controlled current source.
03

Label and complete the sketches

Lastly, label each of the elements on the sketches with the correct value and symbol. Make sure that all connections have been accurately illustrated, and that each aspect of the sketch is clear and readable.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The input impedance to a common-emitter transistor amplifier is \(1.2 \mathrm{k} \Omega\) with \(\beta=140\), \(r_{o}=50 \mathrm{k} \Omega\), and \(R_{L}=2.7 \mathrm{k} \Omega\). Determine: a. \(r_{e}\) b. \(I_{b}\) if \(V_{i}=30 \mathrm{mV}\). c. \(I_{c}\). d. \(A_{i}=I_{o} / I_{i}=I_{L} / I_{b}\). e. \(A_{v}=V_{o} / V_{i}\)

Can you think of an analogy that would explain the importance of the dc level on the resulting ac gain?

a. Sketch the Giacoletto (hybrid \(\pi\) ) model for a common-emitter transistor if \(r_{b}=4 \Omega\), \(C_{m}=5 \mathrm{pF}, C_{u}=1.5 \mathrm{pF}, h_{o e}=18 \mu \mathrm{S}, \beta=120\), and \(r_{e}=14 .\) b. If the applied load is \(1.2 \mathrm{k} \Omega\) and the source resistance is \(250 \Omega\), draw the approximate hybrid \(\pi\) model for the low- and mid- frequency range.

a. What is the expected amplification of a BJT transistor amplifier if the de supply is set to zero volts? b. What will happen to the output ac signal if the dc level is insufficient? Sketch the effect on the waveform. c. What is the conversion efficiency of an amplifier in which the effective value of the current through a \(2.2-\mathrm{k} \Omega\) load is \(5 \mathrm{~mA}\) and the drain on the \(18-\mathrm{V}\) de supply is \(3.8 \mathrm{~mA}\) ?

a. Given an Early voltage of \(V_{A}=100 \mathrm{~V}\), determine \(r_{o}\) if \(V_{C E_{e}}=8 \mathrm{~V}\) and \(I_{C_{Q}}=4 \mathrm{~mA}\). b. Using the results of part (a), find the change in \(I_{C}\) for a change in \(V_{C E}\) of \(6 \mathrm{~V}\) at the same \(Q\) -point as part (a).
See all solutions

Recommended explanations on Physics Textbooks

Physics of Motion

Read Explanation

Energy Physics

Read Explanation

Translational Dynamics

Read Explanation

Electricity and Magnetism

Read Explanation

Astrophysics

Read Explanation

Electricity

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free