Optical receiver to enhance dynamic range thereof
AssigneeSumitomo Electric Industries, Ltd.
InventorKeiji Tanaka
Life of this patent
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Abstract
An optical receiver with an expanded dynamic range for an input current is disclosed. The optical receiver includes a photodiode to generate a photocurrent, a trans-impedance amplifier (TIA) to convert the photocurrent into a voltage signal, a dummy TIA with a same arrangement as that of the TIA to generate a reference, a differential amplifier to amplify a difference between the voltage signal and the reference, a current source to extract a portion of the photocurrent, and a level detector to detect an average photocurrent and adjust the reference based on the average photocurrent.
Claims4
An optical receiver to receive an optical signal, comprising:
- a photodiode to generate a photocurrent corresponding to the received optical signal;
- a first trans-impedance amplifier (TIA) to convert the photocurrent into a voltage signal,
- a second TIA having a same arrangement as an arrangement of the first TIA, the second TIA outputting a reference;
- a differential amplifier to amplify a difference between the voltage signal and the reference, the differential amplifier outputting two outputs complementary to each other;
- an offset canceller to extract a portion of the photocurrent based on the outputs of the differential amplifier;
- and
- a level detector to detect an average of the photocurrent, the level detector outputting a control current to the second TIA to vary the reference,
- wherein the first TIA and the second TIA each have a first stage amplifier including a first bipolar transistor and a second stage amplifier including a second bipolar transistor, the second stage amplifiers of the first TIA and the second TIA respectively outputting the voltage signal and the reference,
- wherein the second TIA receives the control current from the level detector, the control current varying a current flowing in the second stage amplifier of the second TIA,
- wherein the second stage amplifier of the second TIA includes a load resistor, the second bipolar transistor, and an emitter resistor connected in series between a power supply and ground, the reference being output as a voltage drop caused in the load resistor by a collector current flowing in the second stage amplifier of the second TIA, and
- wherein the control current is provided to the emitter resistor to decrease the collector current in the second stage amplifier of the second TIA.
An optical receiver to receive an optical signal, comprising:
- a photodiode to generate a photocurrent corresponding to the received optical signal;
- a first trans-impedance amplifier (TIA) to convert the photocurrent into a voltage signal,
- a second TIA having a same arrangement as an arrangement of the first TIA, the second TIA outputting a reference;
- a differential amplifier to amplify a difference between the voltage signal and the reference, the differential amplifier outputting two outputs complementary to each other;
- an offset canceller to extract a portion of the photocurrent based on the outputs of the differential amplifier;
- and
- a level detector to detect an average of the photocurrent, the level detector outputting a control current to the second TIA to vary the reference,
- wherein the first TIA and the second TIA each have resistors and transistors, the resistors in the second TIA having resistances greater than resistances of the resistors in the first TIA by a size factor m, the transistors in the second TIA having a size of 1/m of a size of the transistors in the first TIA, and
- wherein the second TIA has a power consumption smaller than a power consumption of the first TIA.
Dependencies are inferred from the claim text.