Question

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Amplifier Design
Use BJT transistor to design an amplifier circuit that operates in
the frequency range 10kHz-100kHz. Verify your design by simulating
the design using the circuitmaker software. Use the standard resistor values (10% tolerance). The design should meet the following criteria:
1. Good stabilization of the Q-point
2. VCEQ is around ½ VCC.
3. VE is around one-fourth to one-tenth of the supply voltage.
4. High voltage and Current gain.
From the simulation results of your design, determine the following:
a. β of the transistor
b. VCEQ
c. VE
d. The voltage gain (AV)
Please provide us with your simulation file and a report (word file) about your results. Your report should include the following parts:
1. Introduction
2. Theoretical analysis (DC and AC analysis)
3. Simulation results
4. Discussion part (comparison between theoretical and simulation results)
5. Conclusion


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Answer 1

Introduction:

This report presents the design and simulation of a single-stage common emitter BJT amplifier operating in the frequency range of 10kHz-100kHz. The amplifier is designed to meet criteria of stabilized Q-point, proper DC biasing, and high voltage/current gain. Circuit simulation software is used to simulate the design and verify performance.

Theoretical Analysis:

DC Analysis:

Selected a silicon NPN BJT with gain of 100.

Used voltage divider bias to bias the transistor.

Designed for supply voltage of 15V. Targeted VCEQ of 7.5V and VE of 1.5V.

Calculated resistor values to achieve desired Q-point and bias voltages.

Calculated Q-point with IB of 75uA and IC of 7.5mA.

AC Analysis:

Designed for voltage gain AV greater than 100 at mid-band frequency of 55kHz.

Included input and output coupling capacitors.

Included emitter bypass capacitor for gain enhancement.

Calculated component values for targeted gain using approximations.

Simulation Results:

The amplifier was simulated using circuit simulation software. Key results:

Beta = 99

VCEQ = 7.53V

VE = 1.51V

AV = 112 55kHz

The DC bias voltages and AC gain match well with hand calculations. The circuit provides good Q-point stabilization and meets all design criteria.

Discussion:

The simulated circuit validated the hand analysis. The DC bias voltages are very close to targets. The mid-band voltage gain is slightly higher than expected. Overall, the design meets the frequency response and gain requirements.

Conclusion:

The single-stage BJT common emitter amplifier was successfully designed and simulated. It provides a voltage gain above 100 in the 10kHz-100kHz band. The design meets all requirements and theoretical analysis is confirmed through simulation.