In this chapter, the design and performance of single-amplifier and multiple-amplifier active-RC and active-R(C) biquad circuits has been considered. Negative-feedback single-amplifier circuits have been shown to have low-Q sensitivities to passive components but large ωo and Q sensitivities to the Op Amp GB. The latter property restricted negative feedback circuits to low Q. On the other hand, positive-feedback circuits have been shown to offer the ability of trade-off between active and passive sensitivities and can be designed for higher Q than the negative-feedback circuits.