New Trends in Circuit Design for Analog Signal Processing H. Hakan Kuntman Istanbul Technical University Electronics and Communication Engineering Department Faculty of Electrical and Electronics Eng. 34469, Maslak, Istanbul, Turkey kuntman@itu.edu.tr Abstract A large number of circuit topologies have been proposed in the literature for analog signal processing such as active filters, oscillators, immittance simulators etc. At the beginning, let’s say until twenty years ago, the researchers were proposing this type circuit topologies without giving any realization circuit and application example. Therefore, the main problem was how to realize these topologies and how to apply them to practical work. Another important missing main factor was the influence of the limitations caused by the realization topologies and employed active elements such as bandwidth, slew-rate, input and output impedances etc. With the advances in modern technologies such as CMOS, BiCMOS etc., it is possible today to realize simply these type topologies for analog signal processing; as a result, it is no more sufficient and meaningful to propose only these type circuit without considering the above mentioned items. The trend in analog circuit design is now also to demonstrate how to realize the circuit proposed, what are the limitations of circuit performance and what kind of applications these circuits can find in practical world or how to pick-up the desired output signal? It is a well-known fact that there is a large application area of analog signal processing ranging from very low frequencies at several Hz levels of biomedical signals to RF applications operating at GHz level, from EEG signals to cognitive radio and encrypted communications or low-noise amplifiers in wireless communications. Therefore the designer should know the limitations that influence the performance of his circuit before realization phase. In other words, without considering the circuit from the point of view of microelectronics and realization technology the work performed is incomplete. This paper covers the main features combining the circuit design with the actual realization circuit demonstrating several performance limitations on chosen circuit examples.