Digital Automatic Gain Control Apparatus and Method in Burst Mode Optical Receiver
First Claim
1. A digital automatic gain control method in a burst mode optical receiver having an optical detector and a transimpedance amplifier for converting an output current signal of the optical detector into a voltage signal, the digital automatic gain control method comprising:
- detecting a bottom holding level of the outputted voltage signal when a burst begins;
generating a reset signal using a reference voltage generated according to an output signal of the transimpedance amplifier;
comparing the detected bottom holding level with an input signal; and
controlling a gain of the transimpedance amplifier by generating an automatic gain control signal according to the comparison result.
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Accused Products
Abstract
A transimpedance amplifier for a burst mode optical communication converts a burst current signal into differential output voltage signals. Using a multi-level digital AGC mechanism, the transimpedance amplifier is rapidly adapted to a burst signal whose amplitude varies in a wide range. By using an adaptive level detection method, a multi-level digital AGC can be implemented without using ADC. In addition, because the transimpedance amplifier uses a selective reset generation scheme that performs a reset operation for itself after a high power burst, a burst mode operation can be performed without external reset signals. Accordingly, the transimpedance amplifier can be integrated with an optical detector within a TO-can. Furthermore, the transimpedance amplifier can have the burst mode capability and the best sensitivity.
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Citations
16 Claims
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1. A digital automatic gain control method in a burst mode optical receiver having an optical detector and a transimpedance amplifier for converting an output current signal of the optical detector into a voltage signal, the digital automatic gain control method comprising:
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detecting a bottom holding level of the outputted voltage signal when a burst begins; generating a reset signal using a reference voltage generated according to an output signal of the transimpedance amplifier; comparing the detected bottom holding level with an input signal; and controlling a gain of the transimpedance amplifier by generating an automatic gain control signal according to the comparison result. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A digital automatic gain control apparatus in a burst mode optical receiver having an optical detector and a transimpedance amplifier for converting an output current signal of the optical detector into a voltage signal, the digital automatic gain control apparatus comprising:
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an automatic gain controller for detecting a bottom holding level of the outputted voltage signal when a burst begins, controlling a gain of the transimpedance amplifier by generating at least one automatic gain control signal according to the detected bottom holding level, and generating a reset signal using a reference voltage generated according to an output signal of the transimpedance amplifier; a comparator for comparing the detected bottom holding level with an input voltage, generating a first comparison signal notifying if the automatic gain controller is enabled to generate the reset signal, generating a second comparison signal to enable the reset signal to be generated using the reference voltage, and comparing the detected bottom holding level with the input voltage to output a third comparison signal to enable the automatic gain controller to generate the automatic gain control signal; and a reference voltage generator for generating the reference voltage to the comparator. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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Specification