Electronic Circuit & Systems Design – Cheap Research Essays

Department of Engineering and Design
Electronic Circuit & Systems Design

ASSIGNMENT
You are required to write a report on the following experiments. Experiments should be carried out using an electronic
simulation software package such as Multisim. Multisim is available on all of the open access computer labs in the Richmond
Building; a student version is also available to download from the National Instruments website. Feel free to use an
alternative electronic simulation package if you wish. Please pay particular attention to the questions asked in the
assignment and to the guidance given on which data need recording.
Each experiment is worth 50%, credit will be gained for:

• Detailed design work including calculations
• A concise description of the measurements made
• Answers to all questions posed in this Laboratory Handbook
• A well-presented and organised report
• Multisim simulations must be included in your report where appropriate (and attached within the report, not just
enclosed loosely in the report).

MULTISIM (ELECTRONICS WORKBENCH) SOFTWARE
Multisim is a combined circuit simulation and virtual instrument package. It provides a useful introduction into modern
design procedures by allowing rapid evaluation of a circuit in a style which is very close to practical testing.
Components are selected by clicking on a bin button to fill the bin and then dragging them onto the workspace using the
mouse. The circuit is wired by pointing to the terminal of a component, clicking, and dragging a wire to the next one.
Nodes are automatically created when wires are joined.
The test instruments available to drag onto the workspace which may be required for this lab course are:
1) Multimeter: ac/dc current, ac/dc voltage, resistance
2) Function generator: sine; triangle; square, adjustable frequency; voltage;
offset and duty cycle
3) Oscilloscope: two channel with ac/dc coupling and trigger input
4) Bode plotter: Two channel spectrum analyser capable of plotting
frequency response in conjunction with the function generator

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EXPERIMENT 1: THE BIPOLAR TRANSISTOR
AIMS
• Design a common emitter amplifier circuit using a bipolar transistor
• Show all design calculations
• Demonstrate an understanding of transistor operation with the use of simulated results

COMMON EMITTER AMPLIFIER – DESIGN WORK
• The common emitter amplifier should be designed to operate at midpoint bias; this should be achieved by using a
voltage divider bias network.
• SHOW ALL CALCULATIONS: Calculate all required component values for the circuit to provide a gain of x30 assuming a
collector current Ic = 10mA and ß = 400.
• Choose appropriate input and output coupling capacitors to allow the circuit to function properly down to ~20 Hz.
• Estimate the input and output impedances of the amplifier you have designed
• Construct the circuit in Multisim with appropriate component values.

MEASUREMENTS
For each measurement provide a brief description or an image showing how you achieved the results i.e. where did you put
the measurement device and what type of measurement device did you use?
1) Check and record the collector-emitter voltage (VCE)
• Does this agree with your design? If not, explain why.

2) Measure the collector current (IC = VC/RC) for the quiescent state before you apply a signal.
• Does this agree with your design? If not, explain why.

3) Measure the gain of the amplifier, by comparing Vout with Vin using the two channels of the oscilloscope, over the
full range of frequencies available on the signal source. Record the measurement in your logbook (about ten spot frequency
measurements should be sufficient).
• Plot the results (Gain vs Frequency) in your report.

4) Calculate a suitable value for a bypass capacitor in parallel with the emitter resistor, add the capacitor to your
simulation and repeat the gain measurements from 3.
• Plot the results on the same graph
• Calculate the gain of the circuit; explain any differences from the results found in 3.
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Remember to include:
• All design calculations.
• A description of how each measurement was achieved.
• Detailed discussion about why any differences occurred between your design work and the measured results from your
simulations.

EXPERIMENT 2: THE OPERATIONAL AMPLIFIER
AIMS
• Investigate the operation of an inverting and non-inverting amplifier.
• Show all design calculations and circuit diagrams.
• Answer all questions posed in the measurement section.
• Demonstrate an understanding of the limitations of operational amplifiers with the use of simulated results.

INVERTING AND NON-INVERTING AMPLIFIERS – DESIGN WORK
• Choose a 741 amplifier from the Multisim component library.
• Design two amplifier circuits to have gains of x900:
1. Inverting
2. Non-Inverting
MEASUREMENTS:
1) Measure the gain of your amplifiers at 30 Hz using the signal generator and oscilloscope:
• What is the maximum peak to peak voltage you can apply at the input while still seeing an undistorted sine wave at
the output?
• What is the maximum peak to peak output voltage?
2) Increase the frequency, and take measurements (~10) until the -3 dB point is reached:
• Record this corner frequency
• Plot the results (Gain vs Frequency) in your logbook.
3) Use a DVM to record the DC offset at the output with the input of the amplifiers shorted to 0V.
4) Estimate the input impedance of each amplifier circuit.
5) Construct a low pass filter with a corner frequency of 1kHz by modifying one of your previous designs using the
following circuit and set the voltage gain to be -20x.