NG3S901 Electronics Design

Assignment: Performance Analysis of linear regulator circuits using

Electronics Workbench

In this assignment you will be required to use NI Multisim or similar to simulate electronic circuits with the aim of investigating how well different linear regulator circuits for linear power supplies perform.

Basic requirements:

You need to conduct the following simulations on at least 2 basic regulator circuits:

Zener diode emitter follower regulator

Zener diode emitter follower with error amplifier regulator

Design your regulators so that they have an output voltage of 14V and regulate over an output current range of 100 to 1000mA

You can use features like current probes, voltage probes, oscilloscope or DC-sweep to name but a few to investigate the behaviour of the regulator circuits you have constructed in the simulation. You should at least investigate and demonstrate with sufficient examples the following:

Line voltage regulation

Load variation regulation

Ripple reduction (worst case will be under heaviest load)

In your report make a clear comparison between the behaviour of the 2 circuits under varying conditions and indicate which circuit behaves best, with what kind of effort. Tables comparing the different regulations and ripple reductions may come in handy here.

The main aim of this assignment is that you demonstrate that you can use a circuit simulation software to investigate successfully the most critical aspects of certain circuits, here regulators. Please include sufficiently clear screen shots of your circuits, which need to also include a demonstration of how the circuit regulates. For example, you could show screen shots of the circuit with current and voltage probes showing the output voltage at different load conditions. Show the extreme values (max, min) and one or so intermediate stage, even if you have simulated more conditions in order to investigate the circuit behaviour fully, the results of which can be summarised in tables.

Also show suitable screen shots for the ripple voltage reduction ability of the different circuits and try to quantify this with the simulations.

Advanced investigations:

The assignment is open ended (although to a deadline), so other more advanced aspects than the basic configurations listed above should also be investigated.

The following list gives a small selection of an incomplete list of suggestions of possible aspects that could be investigate, for example: Replacing a transistor error amplifier with an op-amp one, optimising Zener voltage against error amplifier feedback voltage divider (with regards to regulation), reservoir capacitor size against error amplifier layout, short circuit protection, variable current limiter/short circuit protection, variable output voltage etc etc.

Overall Analysis:

The key performance indicators of the more advance solutions should again be compared with those of the basic circuits. Key performance indicators are the line and load regulation as well as ripple voltage. All circuits should be compared with each other after respective analysis.

Report Writing:

Provide a clear well written technical report summarising your approach, motivation, results and analysis. Keep the wording brief but sufficient for the reader to understand your findings. Provide qualified analysis of your results, which is nicely presented and easy to follow. You may also consider cost/technical effort/performance relationships in investigation.