In this lab we will play with a biquad active filter and explore both its basic capabilities and ways of obtaining new filter designs by transforming an existing filter.

1. Design and build a lowpass biquad with a 3-dB frequency of 1 kHz and a pole quality factor (Q) of 0.707 (this gives the maximally flat Butterworth response).

1. Experimentally determine the 3-dB frequency, and mid-band gain of the filter.
2. Sketch the frequency response in your notebook.
3. Exchange C1 and R1 as well as C2 and R2, what effect does this have on the frequency response? Can you explain it?

1. 2. Choose new component values to achieve Q = 5. Repeat your measurements of part 1, paying particular attention to the frequency response around 1 kHz.

1. 3. Use frequency scaling to shift the cutoff of your filter to 10 kHz. Verify your design.