Oscillatory limits of filters containing compounded pairs of operational amplifiers

An enhanced negative-feedback bandpass filter using a double-device composite amplifier is analysed under linear and nonlinear conditions. Extended frequency range is found to be achieved only by stringent design, avoiding instability and restricting signal level. Of the various means suggested for minimising the dependence of filter performance on active device parameters, that employing composite operational amplifiers (COAs) appears to offer considerable promise (see S. Michael et al. 1987). At the expense of additional amplifiers, the small-signal frequency range is usefully extended. From the point of view of integrated-circuit implementation, the chip area and power consumption are less than for the equivalent number of single operational amplifiers