Performance analysis and comparison of multiple loop feedback OTA-C filters

This paper is concerned with performance analysis and comparison of multiple loop feedback (MLF) operational transconductance amplifier and capacitor (OTA-C) filters. General formulas for analysis of sensitivity, maximum input signal and noise based on the matrix method of MLF OTA-C filters are derived for canonical and noncanonical all-pole and finite transmission zero architectures. These formulas can be readily used for performance evaluation of any MLF filters. For illustrating the use of the formulas and comparison of different structures, the performances of inverse-follow-the-leader-feedback (IFLF), leapfrog (LF), and cascade MLF OTA-C filters are simulated ideally and at CMOS transistor level, realizing the same lowpass Butterworth characteristic and using the same OTA. Results show that the LF filter has the lowest passband magnitude sensitivity, highest maximum input signal, and best magnitude response, whilst the cascade filter has the lowest group delay sensitivity, best noise performance and best group delay response. Results also reveal that the IFLF filter has better passband magnitude sensitivity than the cascade filter and better passband group delay sensitivity than the LF filter, but it is the worst in other performances.