Posted: August 4th, 2015

ENGD1019 Computer Aided Engineering, Electronics CAD assignment

ENGD1019 Computer Aided Engineering, Electronics CAD assignment

Assessment: by logbook and demonstration, marked in the laboratory sessions
Assessment weeks: 29 and 30 (in scheduled laboratory sessions)
Anonymously marked: No (individual demo/logbook with feedback given at the time).
Aims
To work through an exercise using a suitable simulation program to demonstrate the operation
of an electronic circuit. The circuit will be provided. The lectures will work through the design,
so you will have the processes demonstrated.
This assignment consists of the following three steps
1. To correctly enter a schematic using the schematic capture component of a suitable
simulation program.
2. To run a behavioural simulation of the electronic circuit.
3. To produce a simple PCB layout for the circuit
Assessment is by logbook and demonstration. You will be expected to attend the laboratory
sessions scheduled in weeks 29 and 30 to demonstrate your CAD design and logbook to the lab
tutor. You should keep and maintain a logbook for the duration of the assignment, using it to
make notes pertinent to the CAD design you are working on. It should have entries that are
dated and in chronological order.
No formal report is required.
Step 1 (20 marks)
The circuit you will be working from is an inverting amplifier based around an operational
amplifier. See Figure 1 below. This is the initial circuit. You will need to show that you have
entered the circuit correctly and in a readable fashion using your chosen CAD package. NOTE:
it does not need to look exactly like Figure 1 – in fact it shouldn’t. It can be drawn in a much
more readable way – so please experiment with this and see if you can present the circuit in a
clearer way. Experimentation is the name of the game here.
Step 2 (40 marks)
Mathematically analyse the circuit and give the inputs and expected outputs using different
values of resistors R1 and R2.
Apply the inputs to the simulation, carry out the simulation and explain the results. Compare the
results to your mathematical solution, You may need to do some reading up to understand how
the operational amplifier works – if you haven’t already encountered it in ENGD1004. There is a
document on Blackboard in the ENGD1019 shell that explains the operational amplifier – read
this. During your demonstration you will need to show that you can simulate a circuit. The basic
simulation will be demonstrated in lectures, but you will need to go further than the basic
demonstration. Show what happens if the input voltage is increased – is there a maximum? At
what point does the output start to distort..and why? What is the ‘gain’ of the amplifier? These
questions, and more, are food for your logbook and demonstration.
Step 3 (40 marks)
Printed Circuit Board (PCB) – this is the common substrate upon which electronic circuits are
built. In this step you will design a printed circuit board. The basic process will be demonstrated
in the lectures, and you will need to refer to this – and the lab tutor – for assistance as this may
well be the first time you have encountered PCB design using CAD. You will be expected to
design a printed circuit board no bigger than 50mm x 50mm (it can be smaller). During your
demonstration you should be able to show how you change and modify tracks, components and
positioning. You should also add your name as a text in the copper layer. The board can be
single or double sided.
Assessment criteria:
MARK ASSESSMENT
>70 Correctly interprets and satisfies all tasks AND provides evidence of SUBSTANTIAL
personal contribution.
60-70 Correctly interprets and satisfies all tasks AND provides evidence of SOME personal
contribution.
50-59 Correctly interprets most tasks with LITTLE evidence of personal contribution. No
major errors.
40-49 Correctly interprets and satisfies most tasks with some minor errors.
Figure 1: Initial operational amplifier
30-39 Fails to interpret and satisfy some tasks.
<30 Fails to interpret and satisfy most tasks. Fails to attend for demonstration/logbook
assessment