A student decided that she needed a low-pass filter that had a roll-off of 2 or 40dB/decade, with a cutoff frequency of 1000 rad/s. She correctly designed two identical passive RC filters, each with a cutoff of 1000 rad/s, and connected themin cascade or one after the other. She cleverly separated them with a buffer to avoid loading. When she measured the cutoff frequency she was dismayed to discover that it was not 1000 rad/s although the roll-off was correct.

(a) Simulate the cascaded pair and determine where the actual cutoff frequency occurs.

(b) Help the student by altering her design so that the two identical RC filters actually produce the desired outcome.

Explain why the discrepancy occurred.