2019 Solution 04

Consider the non-inverting amplifier configuration above with an ideal opamp having a finite gain A.
Choose the best answer that reflects circuit behaviour. ​
​​
​(a) Low pass filter​
​(b) High pass filter​
​(c) Band pass filter​
​(d) Band reject filter
At low frequencies the capacitor is like an open and the feedback is a simple resistor feedback, resulting in some finite but small gain ~ (1+k), k > 1. ​​​​At higher frequencies, the capacitor reduces the signal being fed back, causing a larger error which gets amplified by either (i) (1+k) or (ii)  the larger gain A at manifests at very high frequencies. In any case, the result is a larger output amplitude at higher frequencies leading to a HPF characteristic.​​​​
​​​​R = 10kΩ, C = 1μF, k = 1.58, Avol = 20, BW = 1MHz