Electronic Circuits with MATLAB, PSpice, and Smith Chart

6Analog Filter

CHAPTER OUTLINE

1. 6.1 Analog Filter Design
2. 6.2 Passive Filter
   1. 6.2.1 Low‐pass Filter (LPF)
   2. 6.2.2 High‐pass Filter (HPF)
   3. 6.2.3 Band‐pass Filter (BPF)
   4. 6.2.4 Band‐stop Filter (BSF)
   5. 6.2.5 Quality Factor
   6. 6.2.6 Insertion Loss
   7. 6.2.7 Frequency Scaling and Transformation
3. 6.3 Passive Filter Realization
   1. 6.3.1 LC Ladder
   2. 6.3.2 L‐Type Impedance Matcher
   3. 6.3.3 T‐ and П‐Type Impedance Matchers
   4. 6.3.4 Tapped‐C Impedance Matchers
4. 6.4 Active Filter Realization
5. Problems

This chapter discusses how to design and realize analog filters in the form of passive filters and active filters.

6.1 Analog Filter Design

Figure 6.1(a)‐(d) shows typical low‐pass/band‐pass/band‐stop/high‐pass filter (LPF/BPF/BSF/HPF) specifications on their log magnitude, 20log₁₀|G(jω)| [dB], of frequency response. The filter specification can be described as follows:

(6.1.1a)

(6.1.1b)

where ω_p, ω_s, R_p, and A_s are referred to as the passband edge frequency, the stopband edge frequency, the passband ripple, and the stopband attenuation, respectively. The most commonly used analog filter design techniques are the Butterworth, Chebyshev I, II, and elliptic ones ([K-2], Chapter 8). MATLAB has the built‐in functions ‘butt()’, ‘cheby1()’, ‘cheby2()’, and ‘ellip()’ for designing the four types of analog/digital ...