(a) Design a 2nd order Sallen and Key low pass active filter with the following characteristics:
Nominal Cut-off Frequency: 1.6 kHz
Variable Gain: 0 to 7.5 dB
You may assume that R1 = R2 = R3 and that C1=C2.
(b) Simulate the frequency response for the designed active filter for five values of gain in the range 0 dB to 7.5 dB. Comment on the variation in the cut-off frequency and Q-factor of the variable gain filter.
(c) Build the designed active filter using the μA741 operational amplifier and via a time domain approach show that the response of the filter changes from overdamped to underdamped, with an increase in filter gain. Explain this phenomenon.