David O' Donnell

BSEL2

Active Filter Project

The main objective of the project was to compare results of  active filters and op-amps , with the relation to theoretical, simulated and practical results. To complete this task, Microsim, an Electronic Computer Aided Design ( ECAD ), package was used. This allowed a simulated set of results to be compared with those of a theoretical and practical environment. The project was divided into three main sections, the first being an Operational Amplifier.

The second stage of the project involved re-creating a schematic of a low pass Active Filter. The circuit was then constructed and tested.

• Schematic
• Waveform
• Results

The final task of the project was the design of an High-Pass active filter. The filter was given the design specifications as following;

Active, high-pass, Butterworth filter

Gain in passband = unity (1)

Cut-off frequency = 300 Hz

Roll-off = 40db/decade

The first stage of the design was to determine what values of components to use for the specified criteria.

• Component Selection

The circuit was captured on Microsim and simulated. The circuit was then constructed and tested. The results of these tests are shown below.

• Schematic

• Waveform

• Results

It can be concluded that there was a difference between theoretical, simulated and practical values for circuit design. The theoretical values cannot be achieved as it it assumed that the components are perfect and no energy loss exists. The simulation values however, reflect a more accurate representation of the real world, although cannot take into account energy losses due to poor soldering, or any other human error.  These are portrayed in the actual practical results.