Question

3. Question 3 (10 marks): By cascading a LPF and a HPF as shown in the figure below, one can design a wideband BPF. Provide such a design for the case in which the midband gain is 12dB and the 3dB bandwidth extend from 50Hz to 50KHz. Select appropriate component values under the constraint that no resistors higher than 100K are to be used, and that the input impedance is to be as high as possible. 4 +20 dB/decade -20 dB/ decade So 12 dB 50 Hz 50 kHz -20 dB/decade 0 dB + 20 dB/decade 50 Hz SO KH

Answer 1

The solution to the problem is explained in the images. Please refer it. Thank you.
R? SOLUTIONS, I w R3 circuit will be The input scristance for this given by YERI Zin=R1 Since according to the given to make the input impedance - possible. The maximum value question we have as high as allowable is look - So Ri= look] for the LPF is 50KHZ OTT RC Now, cutoff frequency E FIRE I 50kuz = a treci A Raci = -① 50RHZ 2TRAC, 1OOTTXIO cutoff frequency for the UPF is 50Hz. 50 QUR2 C3 - R32 = UOT -

ne given je 2dB. midband gain 2010g10 A = 1206 be equal to the of LPF and the - The midband gain o will product of maximum gain maximum gain of HPF. ic A= (ALPF) X (AMPF max max ma since, Ri= 100K So, 3.98X100 = R2 X Ry R3 398 = (R2)X R4 - © I dividing 0 and ③ we get R3 Selecting , Ra=loop) and (R3 = lok) Then, From e:q: 398= 10% XR4 Ru= 39-88]

The value of c. and ca are & (1 3 - 31.83pF 100TT X 10PX 100x103 (2= I . 10OTT X 10X103 3 = 0.310F