Electric Circuits, 9th Edition P60. Designed for use in a one or two-semester Introductory Circuit Analysis or Circuit Theory Course taught in Electrical or Computer Engineering Departments. Electric Circuits 9/e is the most widely used introductory circuits textbook of the past 25 years. As this book has evolved over the years to meet the changing learning styles of students, importantly, the underlying teaching approaches and philosophies remain unchanged. | 566 Active Filter Circuits Finally we need to meet the passband gain specification. We can adjust the scaled values of either Rr or R2 because K R2 Rv. If we adjust R2. we will change the cutoff frequency because oe R2C. Therefore we can adjust the value of R to alter only the passband gain Rr R2 K 15 5 il. The final component values are 7 R2 15 il C pF. The transfer function of the filter is given by rT -31 s The Bode plot of the magnitude of this transfer function is shown in Fig. . Figure The Bode magnitude plot of the Low-pass filter from Example . assessment problem Objective 2 Be able to design filter circuits starting with a prototype and use scaling to achieve desired frequency response and component values What magnitude and frequency scale factors Answer kf 62 knt . will transform the prototype high-pass filter into a high-pass filter with a zF capacitor and a cutoff frequency of 10 kHz NOTE Also try Chapter Problems and . Op Amp Bandpass and Bandreject Filters We now turn to the analysis and design of op amp circuits that act as bandpass and bandreject filters. While there is a wide variety of such op amp circuits our initial approach is motivated by the Bode plot construction shown in Fig. . We can see from the plot that the bandpass filter consists of three separate components 1. A unity-gain low-pass filter whose cutoff frequency is t the larger of the two cutoff frequencies 2. A unity-gain high-pass filter whose cutoff frequency is rocl the smaller of the two cutoff frequencies and 3. A gain component to provide the desired level of gain in the passband. Op Amp Bandpass and Bandreject Filters 567 Figure Constructing the Bode magnitude plot of a bandpass filter. These three components are cascaded in series. They combine additively in the Bode plot construction and so will combine multiplicatively in the y domain. It is important to note
