Offset control for burst-mode optical receiver
AssigneeNEC Corporation
InventorHiroki Yanagisawa
Life of this patent
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Abstract
An optical receiver having a photodiode and a preamplifier includes a charge controller which charges a capacitor depending on an received voltage signal at each burst timing of the burst-mode signal and then discharges the capacitor with a predetermined time constant to produce an amplitude-varying offset component. The current signal of the photodiode is controlled so that the amplitude-varying offset component is canceled out.
Claims20
An optical receiver for receiving a burst-mode signal, comprising:
- a converter for converting the burst-mode signal into a voltage signal;
- a detector for detecting an amplitude-varying offset component from the voltage signal using a discharging characteristic of a capacitor which is charged depending on the voltage signal in synchronization with burst timing of the burst-mode signal;
- and
- a controller for controlling the converter to adjust the voltage signal depending on the amplitude-varying offset component.
An optical receiver for receiving a burst-mode signal, comprising:
- a converter for converting the burst-mode signal into a voltage signal;
- a first offset detector for detecting a dc offset component of the voltage signal to produce a first offset signal;
- a second offset detector for detecting a amplitude-varying offset component of the voltage signal to produce a second offset signal;
- a combiner for combining the first offset signal and the second offset signal to produce a third offset signal;
- and
- a controller for controlling the converter to adjust the voltage signal depending on the third offset signal,
- wherein the second offset detector comprises:
- a charge controller for charging a capacitor depending on the voltage signal for a predetermined time period in synchronization with burst timing of the burst-mode signal and discharging the capacitor with a predetermined time constant to produce an amplitude-varying voltage appearing across the capacitor;
- and
- an amplifier for amplifying the amplitude-varying voltage to produce the second offset signal.
An offset control method for an optical receiver for receiving a burst-mode signal, comprising the steps of:
- converting the burst-mode signal into a voltage signal;
- charging a capacitor depending on the voltage signal for a predetermined time period in synchronization with burst timing of the burst-mode signal;
- discharging the capacitor with a predetermined time constant to produce an amplitude-varying voltage appearing across the capacitor;
- and
- controlling the voltage signal depending on the amplitude-varying voltage to cancel out an offset component corresponding to the amplitude-varying voltage.
An offset control method for an optical receiver for receiving a burst-mode signal, comprising the steps of:
- converting the burst-mode signal into a voltage signal;
- detecting a dc offset component of the voltage signal to produce a first offset signal;
- charging a capacitor depending on the voltage signal for a predetermined time period in synchronization with burst timing of the burst-mode signal;
- discharging the capacitor with a predetermined time constant to produce an amplitude-varying voltage appearing across the capacitor;
- and
- producing a second offset signal from the amplitude-varying voltage;
- combining the first offset signal and the second offset signal to produce a third offset signal;
- and
- controlling the converter to adjust the voltage signal depending on the third offset signal to cancel out an offset component corresponding to the third offset signal.
Dependencies are inferred from the claim text.