Method and apparatus for interference reduction in optical sensing receivers
AssigneeAvago Technologies International Sales Pte. Limited
InventorsJunjie Lu, Jing Guo, Leon Samuel Wang, Xiaofeng Lin, Xicheng Jiang
Life of this patent
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Abstract
An apparatus for detecting optical signals includes a photodetector. The photodetector is reverse-biased by a first voltage and a second voltage is added to the first voltage to provide an offset equal to the second voltage for the photodetector. A first circuit is coupled to the first circuit to provide the second voltage for the photodetector and a second circuit is coupled to the first circuit to provide the first voltage to the photodetector to reverse-bias the photodetector. The second circuit provides an output voltage proportional to a current of the photodetector at an output of the second circuit.
Claims20
An apparatus comprising:
- a photodetector, wherein the photodetector is reverse-biased by a first voltage between a cathode and an anode of the photodetector, and wherein a second voltage is combined with the first voltage to provide an offset voltage for both the cathode and anode of the photodetector;
- a first circuit coupled to the photodetector and configured to provide the second voltage to the photodetector;
- wherein the first circuit comprises an operational-amplifier (Op-Amp), wherein an inverting node of the Op-Amp is coupled between first and second capacitors, an output node of the Op-Amp is coupled between third and fourth capacitors, and a voltage source is coupled between a non-inverting node of the Op-Amp and a ground, and wherein the Op-Amp is biased in a linear region;
- and
- a second circuit coupled to the first circuit and configured to provide the first voltage to the photodetector to reverse-bias the photodetector, wherein the second circuit is also configured to provide a current of the photodetector at an output of the second circuit.
An apparatus comprising:
- a photodetector;
- a first circuit comprising a voltage source, a first port, and a second port, and configured to:
- receive a current at the first port,
- receive a first voltage and a second voltage at first and second nodes of the second port respectively, wherein the voltage source is configured to provide an offset voltage (Vo), and
- provide the first voltage combined with the offset voltage and the second voltage combined with the offset voltage at first and second nodes of the first port respectively;
- and
- a second circuit comprising a first capacitor and a second capacitor, coupled to the second port of the first circuit, wherein the first capacitor and the second capacitor are configured to store charges, wherein the charges of the first and second capacitors are configured to generate the first voltage and the second voltage at the first and second nodes of the second port of the first circuit, wherein voltages at a cathode and an anode of the photodetector are respectively provided as Vo+½VRB and Vo−½VRB.
An apparatus comprising:
- a first circuit that comprises a photodetector;
- a second circuit coupled to the first circuit and configured to provide an offset voltage (Vo),
- a third circuit coupled the second circuit and configured to provide a first voltage (V1) and a second voltage (V2) to a cathode and an anode of the photodetector of the first circuit to reverse-bias the photodetector by a sum (VRB) of magnitudes of V1 and V2, wherein V1 and V2 have opposite polarity and V1 is positive, and wherein:
- voltages at the cathode and the anode of the photodetector are set to Vo+V1 and Vo+V2 respectively,
- voltages at first and second nodes of a first interface between the third circuit and the second circuit are set to voltages Vo+V1 and Vo+V2, respectively, and
- voltages at first and second nodes of a second interface between the second circuit and the first circuit are set to the voltages Vo+V1 and Vo+V2, respectively;
- and
- a fourth circuit coupled to the third circuit and configured to amplify a current of the photodetector, received via the second circuit and the third circuit, and provide an output voltage proportional to the current of the photodetector.
Dependencies are inferred from the claim text.