ABSTRACT
This chapter begins by reviewing briefly the signal flow graph (SFG) method, since this is such a frequently used technique in the design of active filters based on ladder prototypes, including SC filters. It considers the frequency transformations which are available to map the continuous-time ladder filter into the discrete-time domain. The chapter shows how the choice of transformation is constrained by the availability of suitable SC building blocks. There are two general approaches for designing active filters based on LCR ladder prototypes. The first is inductor replacement using an impedance transformation device of which the gyrator and negative impedance converter are perhaps the best-known examples. The second method simulates the electrical terminal properties of the elements of the prototype, which for this purpose is usually represented by its SFG. The chapter presents the operation of the SC integrator.
