다음 사양을 만족하는 아날로그 버터워스 저역통과 필터를 설계하라.

• 통과대역 차단 주파수:; 통과대역 리플 : 
• 저지대역 차단 주파수:; 저지대역 리플 : 

ex8_4.cem

/*   Chapter 8: Example 8.4   Butterworth Lowpass Analog filter design
*/
 
  Wp = 0.2*pi; Ws = 0.3*pi; Rp = 7; As = 16;
  Ripple = 10 ^ (-Rp/20); Attn = 10 ^ (-As/20);
  /* Analog filter design */
  [b,a] = butlpf(Wp,Ws,Rp,As);
 
  /* Calculation of second-order sections */
  [C,B,A] = sdrt2cas(b,a) 
  /* Calculation of Frequency Response: */
  [db,mag,pha,w] = mfreq_s(b,a,0.5*pi);
  /* Calculation of Impulse response: */
  [ha,x,t] = impulse(b,a);
 
 
 
//Plots
 
subplot(2,2,1); plot(w/pi,mag);title("Magnitude Response")xtitle("Analog frequency in pi units"); ytitle("|H|");
 
subplot(2,2,2); plot(w/pi,db);title("Magnitude in dB")xtitle("Analog frequency in pi units"); ytitle("decibels");
 
subplot(2,2,3); plot(w/pi,pha/pi); title("Phase Response")xtitle("Analog frequency in pi units"); ytitle("radians");
 
subplot(2,2,4); plot(t,ha,[0,max(t)],[0,0]); title("Impulse Response")xtitle("time in seconds"); ytitle("ha(t)");