Question

(11 points) [Band-Rejection Filter (BRF)]: You are to choose values for R1. R2 and the components within the dotted box (a resistor R, capacitor C, and inductor L, assembled appropriately) so that the circuit meets the following requirements: It completely rejects a 850Hz signal The bandwidth rejection range is 65Hz (N.B. Use the Q, BW formulas in notes (silent video). LL.) . When Vi (t) 7V2cos (2π × 850t) V, the RLC circuit in the box consumes 35mW When vi(t) 3V (i.e., DC), we require vo(t)-25V and resistor R1 will dissipate 65mW Note: In this problem, you may only submit numerical answers. (i.e. If 4 is the correct answer, 4 will be marked as correct, but 2+2 will be marked as incorrect.) R= S2 C=

Answer 1

Consider the Band rejection filter. C The lower cut-off frequency fz=222 f. = 65 Hz B = 65 Hz The resonant frequency fo=27VLC fo = 850 Hz Consider frequency 850 Hz. v;(t)= 71/2 cos ( 278501) Verme = 7 P=35 mW

35 mW=(7) R = 35 mA R=1.4k 2 Find inductor value L. R. 27165 HZ 1.4 k2 20L = 65 1 - 65(27) - 1.4k L = 291.7 mH Find capacitor value C. fo=27VIC fo = 850 Hz 850 Hz= - (291.7 mHỌC C=0.12 °F For inverting amplifier, the dc gain is, -25V _ -R 3v R = 8.33R The power dissipation through R,resistor is 65 mW

65 mW= 165 mW R2 = 138.462 R2 = 8.33(R) R2 = 8.33(138.46) Ri=1.15 k22