To enable to understand the operations and design of amplifier circuits.
Learning Outcomes:
Sketch typical characteristics of diodes, bipolar and field-effect transistors and solve problems on common-emitter amplifier with resistive loads and tuned-circuit loads.
Task
To design two stage common emitter amplifiers to amplify a very small AC signals from the microphone for the following specifications:
Vin = 0.02V
Frequency range = 100 Hz to 10 kHz
AV1 = 10-30
AV2 = 5-20
β = 235 (PN2222) or 174 (2N3904)
Vcc = 12 VDC
(i) Sketch a DC bias circuit with design values of resistors with power ratings
(ii) Sketch an AC equivalent circuit with calculations of R()IN, and R(OUT).
(iii) Select the suitable capacitive coupling from the signal source to an amplifier and output to the load.
(iv) Draw a complete amplifier circuit with input source and output measuring instruments
(v) Demonstrate the working of the transistor amplifier using the simulation tools and verify the output voltage, voltage gain and compare with the calculated voltage gain. Use 2N3904 or PN2222 transistor, function generator and oscilloscope.
(vi) Plot the frequency responses of the two stage common emitter amplifiers for the frequency ranges from 100 Hz to 10 kHz.
(vii) Evaluate the mid band gain, lower cut-off, upper cut- off frequencies and bandwidth.
Write a report focusing on design and circuit implementation through simulation tool. The report should include an abstract, introduction, design, working principles, implementation through simulation, output, conclusion and list of references but no longer than 1500 words.
Important points:
-Knowledge and understanding of the topic (assessed through demonstration of circuit layout and operations)
-Design, and hardware implementation (Module specific Skill)
-The structure in terms of logic and coherence
-Online queries and discussion
-In text citation and referencing
Sample Solution