Optical receiver with increased dynamic range
An optical receiver with increased dynamic range includes a photodetector, a photodetector biasing network, an amplifier and a post-distortion network. The post-distortion network compensates for gain error in the amplifier, such that a composite output voltage is relatively linear with respect to input current. The dynamic gain responses of the amplifier and the post-distortion network are equal in magnitude and opposite in phase. Additionally, a signal from at least one internal node of the amplifier may be connected to the post-distortion network, in order to further improve performance.
1. An optical receiver comprising:
a photodetector;
a photodetector biasing network connected to the photodetector;
a trans-impedance amplifier having an input connected to the photodetector; and
a post-distortion network connected to an output of the trans-impedance amplifier, and at least one internal node of the trans-impedance amplifier is connected to the post distortion network to provide at least one input signal for the post-distortion network to adjust a gain or loss characteristic of the post-distortion network;
wherein the post-distortion network compensates for gain error in the trans-impedance amplifier, such that a composite output voltage is relatively linear with respect to input current, and wherein the dynamic gain responses of the amplifier and the post-distortion network are equal in magnitude and opposite in phase.
2. The optical receiver of claim 1 , wherein the trans-impedance amplifier comprises a differential trans-impedance amplifier having two inputs and two outputs, and the distortion network has two inputs connected to the two outputs of the differential trans-impedance amplifier.
3. The optical receiver of claim 1 wherein the trans-impedance amplifier comprises a dual trans-impedance amplifier having two inputs and two outputs, and the distortion network has two inputs connected to the two outputs of the dual trans-impedance amplifier.
4. A method for increasing the dynamic range of an optical receiver, the method comprising:
detecting an optical signal with a photodetector, the photodetector biased with a biasing network;
applying an output current from the photodetector to a trans-impedance amplifier;
applying an output signal from the trans-impedance amplifier to a post-distortion network; and
applying a signal from at least one internal node of the trans-impedance amplifier to the post-distortion network to provide at least one input signal for the post-distortion network to adjust a gain or loss characteristic of the post-distortion network;
wherein the post-distortion network compensates for gain error in the trans-impedance amplifier, such that a composite output voltage is relatively linear with respect to input current, and wherein the dynamic gain responses of the trans-impedance amplifier and the post-distortion network are equal in magnitude and opposite in phase.