Filter Design by Impulse Invariance Digital Signal Processing--IIR Digital Filter Design 视 jIm() 3π π Re(z) Z plane S plane ⊙：一兀~亚洛充五大￥Digital Signal Processing—— IIR Digital Filter Design Filter Design by Impulse Invariance jΩ 0 σ T −π T 3π T − 3π T π j Im(z) Re(z) 0 ω S plane Z plane ω : −π ~ π