4/27/98

Consider the following circuit.

1. (20 points) Show that the transfer function for this active filter is

Record your derivation in a Word file named final.doc.

2. (10 points) When C = 0.01 microFarad and R = 10,000 Ohms, plot |T(jω)| vs. ω on an Excel graph. Embed the Excel spreadsheet in the Word file.

3. (10 points) When C = 0.01 microFarad and R = 10,000 Ohms, make a two-dimensional pole-zero diagram for T(s). Include this plot in the Word file final.doc.

4. (10 points) When C = 0.01 microFarad and R = 10,000 Ohms, use the file POLEZERO.XLS to present a three-dimensional view of the pole zero plot for |T(s)|. Embed this Excel file in the Word file final.doc.

5. (10 points) When C = 0.01 microFarad and R = 10,000 Ohms, use PSpice to simulate the circuit and plot |T(jω)| vs. ω. Embed both the PSpice Schematic file, final.sch and a screen shot of the Probe screen that shows |T(jω)| vs. ω in the Word file. Compare the results of the PSpice simulation with the Excel graph.

6. (40 points) Construct the circuit above with C = 0.01 microFarad and R = 10,000 Ohms and use the Cool Edit sound editor running on a PC with a full-duplex sound card (SoundBlaster SB16, SB32, AWE32, or AWE64, for example) to measure the magnitude of the transfer function, |T(jω)| vs. ω. Specifically, connect the line output of the sound card to the input of the active filter and use one instance of Cool Edit to generate a sinusoid whose frequency sweeps from 20 to 20,000 Hz during a 10 second interval. With a second instance of Cool Edit, record the input to the circuit, V_in, in the left stereo channel of the line input and the output of the circuit, V_out, in the right stereo channel of the line input. In the Word file, embed a screen shot of the Cool Edit screen that shows the recorded input and output signals.

Use Cool Edit to display the Fourier spectrum of the output recorded from the active filter. In the Word file, embed a screen shot of the Cool Edit screen that shows the Fourier spectrum.

In the Word file, discuss how the shape of the Fourier spectrum should relate to the shape of |T(jω)| vs. ω. Then, compare your measurements with your earlier calculations with PSpice and Excel and discuss the extent to which they agree.

The 3.5 inch floppy disk that you submit should include a ZIP file, named final.zip, that should contain the Microsoft Word file, final.doc, and the final.wav file, both in a directory named final. The disk should have a label that shows the following:

Place your circuit in the plastic video cassette case provided, and submit it and your floppy disk in the large brown envelope.