Patent ID: 6836185
Filing Date: 2004-12-28
Classification: G02F,H03F

Abstract:
A modulator driver, comprising:a first amplifier stage (A1) having inputs and outputs, the first amplifier stage comprising a first differential pair of transistors; a second amplifier stage (A2) having inputs and outputs, the second amplifier stage comprising a second differential pair of transistors, the inputs of the second amplifier stage coupled to the outputs of the first amplifier stage; an active load coupled between a supply voltage and the outputs of the second amplifier stage and which produces an output voltage that varies with the electrical current conducted by said second differential pair of transistors, said active load arranged to provide an AC resistance that is greater than its equivalent DC resistance; and a feedback stage (A3) having inputs and outputs, the inputs of the feedback stage commonly coupled to the outputs of the second stage amplifier and the inputs of the active load, the outputs of the feedback stage commonly coupled to the inputs of the second stage amplifier and the outputs of the first amplifier stage.