Abstract: An interface circuit that interfaces a digital-to-analog converter (DAC) to a vertical-cavity surface emitting laser. The apparatus includes a first cascode amplifier that receives as input positive and negative differential outputs of the DAC and provides a positive amplified output and a negative amplified output, and a second cascode amplifier having a positive input and a negative input. The positive input of the second cascode amplifier being coupled to the positive amplified output of the first cascode amplifier. The second cascode amplifier is configured to generate a positive amplified current and a negative amplified current at a negative amplified output. The positive amplified current and the negative amplified current are combined and a resulting output current is provided as input to an anode of the laser. A transformer is coupled between the negative amplified output of the first cascode amplifier and the negative input of the second cascode amplifier.

Abstract: A method and apparatus that cancels or reduces DC offset in a fully-differential optical receiver. The method includes receiving differential optical signals, converting, with photodetectors, the differential optical signals to differential current signals representative of the differential optical signals, converting, using a transimpedance amplifier, the differential current signals to differential intermediate voltage signals, amplifying, using a main amplifier, the differential intermediate voltage signals to generate differential output voltage signals, and cancelling a DC component of the differential output voltage signals using a fully differential DC cancellation circuit. Output offset may also be cancelled or reduced using digital control.

Abstract: A method and apparatus that cancels or reduces DC offset in a fully-differential optical receiver. The method includes receiving differential optical signals, converting, with photodetectors, the differential optical signals to differential current signals representative of the differential optical signals, converting, using a transimpedance amplifier, the differential current signals to differential intermediate voltage signals, amplifying, using a main amplifier, the differential intermediate voltage signals to generate differential output voltage signals, and cancelling a DC component of the differential output voltage signals using a fully differential DC cancellation circuit. Output offset may also be cancelled or reduced using digital control.