1. A operational transconductance amplifier, comprising: a) a first and second voltage controlled current source circuit configured to provide an output current dependent on the product of the output current of the first voltage controlled circuit, and the quotient of the input voltage of the second voltage controlled current source circuit and the input voltage of the first voltage controlled current source circuit; b) each of said voltage controlled current source circuits having an adaptive transconductance cell connected to a bias, set by a feedback loop.