STUDIES ON SOME DDCC/CCII BASED ALL-PASS FILTERS/ OSCILLATORS

The inherent advantage of Integrated Circuits (ICs) like low cost, miniature size, high speed, high reliability and improved performance over discrete circuits resulted in the evolution of ICs from Small Scale ICs to Very large Scale (VLSI) ICs that are very popular today. In the beginning, analog circuits were widely used. But, because of the advantages of digital domain, digital circuits became more popular. But most of the real-world signals are continuous time signals, i.e., analog signals. Hence analog circuits are still in use. Analog to digital converters (ADCs) are further used to convert the analog signals to digital form, when necessary. The best example for this is the operational amplifier, which is used in many linear as well as non-linear applications. Operational amplifiers have very low output impedance and very high input impedance, open loop voltage gain, slew rate and bandwidth. Thus, they replaced many transistor circuits in various applications like amplifiers, filters, timers, analog multipliers, adders, subtractors, differentiators, integrators, etc. Analog signal processing gives many benefits by processing current signals rather than voltage signals.