Analysis of current conveyor error effects in signal-processing circuits

Abstract

In this paper the modelling, analysis and compensation of current conveyor tracking non-idealities in signal-processing circuits employing the second-generation current conveyor (CCII) as a transconductance amplifier are generally investigated. The voltage- and current-following inaccuracies of the CCII are represented in the forms of absolute and relative errors. Analysis shows that the effects of absolute tracking errors in a non-ideal CCII-based transconductance amplifier can be represented by an ideal CCII transconductance amplifier with an external voltage or current offset source. With this model the circuit output signal shift due to tracking errors can be easily evaluated using any excitation-response circuit analysis method. For the relative error description the effects of CCII following inaccuracies are modelled as a change in the transconductance resistance for the CCII transconductance amplifier. The affected circuit parameters are therefore readily assessed by directly replacing the nominal transconductance resistance in the ideal expressions by the varied counterpart, and the impact of relative errors can thus be precisely compensated by simply adding a proper resistance in parallel or series with the transconductance resistance. The methods developed for conventional CCIIs with unity gains are also extended to incorporate generalized CCIIs with any specified voltage and current gains.