D 2.86 Figure P2.86 shows a circuit that performs a low- pass STC function. Such a circuit is known as a first-order, low-pass active filter. Derive the transfer function and show that the de gain is (-R,/R,) and the 3-dB frequency an = 1/CR,. Design the circuit to obtain an input resis- tance of 10 k2, a de gain of 20 dB, and a 3-dB frequency of 10 kHz. At what frequency does the magnitude of the trans- fer function reduce to unity? R2 R1 V; o w o V. Figure P2.86