Passive, active, and digital filters (3ed., CRC, 2009) - tiera.ru

Multiple-Amplifier Biquads 13-15C 6G 6+–jω+V i–C 4–+G 1G 3G 2G 5+V o–σ(a)G 1 = G 2(b)FIGURE 13.18Second-order all-pass building block. (a) The circuitry. (b) The pole and zero locations.G 6bG 6aC 6G 5G 3G 2+V i–C 4–+G 1+–+V o–jωσ(a)G 2 G 6b = G 1 G 6a(b)FIGURE 13.19Notch filter building block. (a) The circuitry. (b) The pole and zero locations.Finally we will derive two second-order elliptic or Cauer-type building blocks from the general dualamplifierstructure in Figure 13.14b. To get a Cauer low-pass building block we take Y 1a ¼ G 1 , Y 1b ¼ C 1 ,Y 2 ¼ G 2 , Y 3 ¼ G 3 , Y 4 ¼ G 4 , Y 5 ¼ sC 5 , Y 6a ¼ 0, and Y 6b ¼ G 6 ; see Figure 13.20.