Patent ID: 7848369

Claim:
An integrated circuit comprising: a substrate; a modulator driver circuit provided on the substrate for generating a modulator drive signal having an AC component and a DC component, the modulator driver circuit having an input and an output, the input of the modulator driver circuit configured to accept a data signal, the data signal being AC coupled to the input of the modulator driver circuit, the modulator driver circuit providing the modulator drive signal at the output of the modulator driver circuit; an adjustable current source circuit provided on the substrate, the adjustable current source electrically coupled to the modulator driver circuit, such that the adjustable current source circuit controls an amplitude of the AC component of the modulator drive signal; and a controller having an input and an output provided on the substrate, the controller electrically coupled to the adjustable current source circuit, the controller being configured to provide an output command signal on the output of the controller in response to an input command signal received on the input of the controller, the adjustable current source providing a corresponding one of the plurality of currents values in response to the output command signal received from the controller, wherein an adjustable power supply voltage is provided to the modulator driver circuit, such that the modulator driver circuit generates the DC component of the modulator drive signal based on the adjustable power supply voltage, the adjustable power supply voltage being configured to be a differential adjustable power supply voltage including a first variable supply voltage and a second variable supply voltage.