5.1.1 Ideal Frequency-Selective Filters ◆ Ideal highpass filter 1-H(e)=b(a") 0 <W v<w|≤丌 sin w n n=on 0<n<0 元n H 2丌 2丌 66 5.1.1 Ideal Frequency-Selective Filters ◆Ideal highpass filter ( ) 0, 1, jw c hp c w w H e w w     =          sin , c hp w n h n n n n   = − −     − 2 − − wc 0 wc  2 ( ) jw H e 1 1 ( ) jw − H e lp =