DESIGN AND APPLICATIONS OF THE OPERATIONAL FLOATING AMPLIFIER (OFA) -THE MOST UNIVERSAL OPERATIONAL-AMPLIFIER

The operational floating amplifier (OFA) is the most universal type of operational amplifier. Both input and output ports are floating ports , i.e., free from restrictive ground connections. The floating input p ort enables the OFA to accurately equate two voltages between the two input terminals, like a standard operational amplifier, but in additio n to that the OFA is able to accurately equate two currents through th e two terminals of the floating output port. Specific applications are given, such as current amplifiers, voltage-to-current converters, gyr ators, hybrids, and filters. The concept of the OFA allows these analo g transfer functions to be realized with the absolute minimum number o f accurate internal and external elements necessary to accurately dete rmine the transfer. The OFA does not need accurate internal matched el ements, except for offset, to obtain accurate overall transfer functio ns. This is in contrast to other current-output devices, such as the c urrent conveyer, which transfer depends on the accuracy of internal cu rrent mirrors. Several designs of class A and class AB OFAs based on d ifferent topologies are presented and compared. This paper gives an ov erview of the application, the specification, and the design.