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The current conveyor has been around since the original design, or CCI (which can be regarded as an idealtransistor), was iniTIally proposed by Smith and Sedra in 1968¹,². CCI was then replaced by a more versaTIlesecond-generaTIon device in 1970, the CCII³. Current conveyor designs have mainly been BJT due to their hightransconductance values compared to their CMOS counterparts. They are used as current-feedback operaTIonalamplifiers like the MAX477 high-speed amplifier and the MAX4112 low-power amplifier, which both featurecurrent feedback rather than the conventional voltage feedback used by standard operational amplifiers. Thismeans that the current feedback operational amplifier is not restricted by the conventional gain bandwidths of astandard operational amplifier, and can offer a much higher bandwidth solution than its voltage-feedbackcounterpart.Current conveyors are used in high-frequency applications where the conventional operational amplifiers cannotbe used, because the conventional designs are limited by their gain-bandwidth product. In theory, the currentconveyor is only limited by the ft of the transistors used in its design. Some applications where currentconveyors are used today include RF mixers, high-frequency precision rectifiers, and medical applications suchas Electrical Impedance Tomography (EIT).
