AN4198 pdf datasheet

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