Wide bandwidth circuits for high linearity optical modulators

1. Field of the Invention Wide bandwidth compensating circuits are disclosed for compensating for the nonlinearity of other circuits placed in cascade therewith over a relatively wide bandwidth, particularly for high linearity optical modulators, in which first and second versions of a signal are generated having different gains and different nonlinear distortions. The first signal has a higher gain with a lower distortion. The second signal has a lower gain with a higher distortion, and is subtracted from the first larger amplitude signal to form an output signal having a desired nonlinear transfer characteristic over a relatively wide frequency range. A first exemplary circuit has a first higher gain path and a second lower gain path having a transfer characteristic with a substantially greater amount of negative cubic distortion. The first and second signals are subtracted in a wide band differential amplifier to form a resultant signal having a desired positive cubic distortion. Second and third exemplary circuits are also disclosed.