Applied Physics – Instruments Amplifiers Built with Current-conveyors

The current-conveyor has precise unity gain between Z and X (Fig. 1), rather than the high ill-defined open-loop gain of the voltage op-amp, therefore in amplifier applications the current-conveyor is generally used without any overall negative feedback. The advantage of this approach is that the traditional closed-loop gainbandwidth conflict of negative feedback voltage op-amp circuits is avoided. The benefits of global negative feedback, for example noise reduction, improvement in input and output impedance levels, can no longer be exploited, but the absence of overall negative feedback generally results in wider bandwidths at higher levels of gain. However, to maintain a high level of accuracy without the use of negative feedback, a high quality current-conveyor integrated circuit realisation is required.