this book enables readers to become familiar with passive and active realizations of the impedances and important filter transfer functions (tfs). firstly, time, s, and frequency domain analysis of the r-l, r-c, and r-l-c circuits are discussed. then, active realizations of the impedances and tfs using different active devices are introduced. readers will benefit from an example-driven approach to topics such as operational amplifiers, current followers, voltage followers, unity gain inverting amplifiers, negative impedance converters, first-generation current conveyors, second-generation current conveyors, third-generation current conveyors, differential voltage current conveyors, etc. will be introduced, which will be accompanied with a number of examples. non-ideal gain effects on the performance of the active circuits are also demonstrated.