Download EE100Lab Fall 2005: Building and Analyzing Low Pass Filters and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity! 1EE100Lab Fall 2005 Laboratory #7 Simple Low Pass Filters In this lab you will build 1st order and a 2nd order lowpass filters using resistors , capacitors and inductors. Then you will build an “active” 2nd order lowpass filter using resistors, capacitors and an operational amplifier. Equipment: • Knight Electronics Minilab with connecting wires • Goldstar Function Generator • Digital Multimeter • PC with Digital Storage Oscilloscope attachment • 1nF, 2nF capacitors • 10mH inductor • 2 of 2.2kΩ, 1.6kΩ, 30kΩ and 4.3kΩ resistors • Operational amplifier Preparation: • Study sections 6.2, 6.4, 6.8 of the textbook. The equations you need are all there. Some other reading may be required. Description of Experiment A: 1. Connect up the lowpass filter as shown using a 1.6kΩ resistor and a 2nF capacitor. 2. Plot the gain (magnitude in dB and phase shift) of the circuit versus log10f. • Determine f0 by plotting asymptotes on the plot. • Calculate f0 using the formula from the book. Does it agree? • Measure the magnitude and phase of the gain at f0. Does they agree with the theory for a 1 st order lowpass filter? • Measure the slope of the magnitude versus frequency at high frequencies. Does it agree with theory? 2EE100Lab Fall 2005 Description of Experiment B: Repeat Experiment A using a high pass filter constructed by interchanging the R and C of the circuit above. Description of Experiment C: 1. Connect up the 2nd order lowpass filter as shown using a 4.3kΩ resistor, a 1nF capacitor and a 10mH inductor. 2. Plot the magnitude (in dB) and phase shift of the circuit versus log10f. • Determine f0 by plotting asymptotes on the plot. Compare it to the calculated f0. Don’t forget to include the resistance of the inductor. • Measure the magnitude and phase of the gain at f0. Do they agree with the theory for a 2 st order lowpass filter? • Measure the slope of the magnitude versus frequency at high frequencies. Does it agree with theory? • Calculate the Q of the circuit. Don’t forget to include the resistance of the inductor. • Compare your measured results with those in the textbook using the Q you calculated. 3. Apply a square wave to the input of the filter using the function generator. • Adjust the frequency of the square wave to f0/3. • Print the output waveform of the filter • Repeat for frequencies of f0/2, f0 and 2f0. Includes RL 3. Apply a square wave to the input of the filter using the function generator. • Adjust the frequency of the square wave to f0/3. Print the output waveform. • Repeat for square wave frequencies of f0, and 2f0. • Comment on the results. What is happening to change the waveforms?
