OPTICAL RECEIVER, ACTIVE OPTICAL CABLE, AND CONTROL METHOD FOR OPTICAL RECEIVER
원문보기
IPC분류정보
국가/구분
United States(US) Patent
공개
국제특허분류(IPC7판)
H04B-010/69
H03F-003/45
H03F-003/08
G01J-001/44
출원번호
US-0820817
(2017-11-22)
공개번호
US-0109326
(2018-04-19)
우선권정보
JP-2014-211225 (2014-10-15)
발명자
/ 주소
TANAKA, Takayuki
HAYASHI, Minako
출원인 / 주소
FUJIKURA LTD.
인용정보
피인용 횟수 :
0인용 특허 :
0
초록▼
The present disclosure includes a photodetector element (11) that converts an optical signal into an electric current signal; a transimpedance amplifier (12a) that converts the electric current signal into a voltage signal; a differential amplifier (12d) that converts the voltage signal into a diffe
The present disclosure includes a photodetector element (11) that converts an optical signal into an electric current signal; a transimpedance amplifier (12a) that converts the electric current signal into a voltage signal; a differential amplifier (12d) that converts the voltage signal into a differential signal, by performing differential amplification of a difference between the voltage signal and a threshold voltage; an LOS detection circuit that detects a no-signal section of the optical signal; and an MCU that repeatedly executes offset cancellation processing, the offset cancellation processing including threshold voltage change processing in which the threshold voltage is changed such that an offset voltage of the differential signal is reduced, the MCU 13 skipping the threshold voltage change processing in the no-signal section.
대표청구항▼
1. An optical receiver comprising: a photodetector element that converts an optical signal into an electric current signal;a transimpedance amplifier that converts the electric current signal into a voltage signal;a differential amplifier that converts the voltage signal into a differential signal,
1. An optical receiver comprising: a photodetector element that converts an optical signal into an electric current signal;a transimpedance amplifier that converts the electric current signal into a voltage signal;a differential amplifier that converts the voltage signal into a differential signal, by performing differential amplification of a difference between the voltage signal and a threshold voltage; anda control section that repeatedly executes offset cancellation processing, the offset cancellation processing including threshold voltage change processing in which the threshold voltage is changed such that an offset voltage of the differential signal is reduced,at a point at which a sign of the offset voltage inverts, or at a point at which a level of the offset voltage becomes less than a tolerance, the control section reducing a frequency at which the offset cancellation processing is executed. 2. The optical receiver according to claim 1, wherein: the optical receiver includes two or more sets of the transimpedance amplifier and the differential amplifier, the two or more sets corresponding to two or more channels, respectively; andat a point at which there is no longer a channel in which a sign of the offset voltage has not yet inverted, or at a point at which there is no longer a channel in which a level of the offset voltage has not decreased to less than a tolerance, the control section reduces a frequency at which the offset cancellation processing is executed. 3. The optical receiver according to claim 1, wherein: the offset cancellation processing has two execution modes which are different from each other in an amount of change in the threshold voltage during the threshold voltage change processing, the two execution modes including a first execution mode in which the amount of change in the threshold voltage is greater and a second execution mode in which the amount of change in the threshold voltage is smaller; andat a point at which a sign of the offset voltage inverts, or at a point at which a level of the offset voltage becomes less than a tolerance, the control section switches the first execution mode to the second execution mode. 4. The optical receiver according to claim 1, wherein: the control section writes a value of the threshold voltage to a nonvolatile memory either at the time when operation of the control section ends or periodically during the operation of the control section; andat the time when the operation of the control section commences next, the control section reads out, from the nonvolatile memory, the value of the threshold voltage, and uses, as an initial value for the offset cancellation processing, the value of the threshold voltage that has been read out. 5. The optical receiver according to claim 1, further comprising a variable voltage source that generates the threshold voltage, the control section changing the threshold voltage by controlling the variable voltage source. 6. An active optical cable comprising an optical receiver according to claim 1. 7. An optical receiver comprising: a photodetector element that converts an optical signal into an electric current signal;a transimpedance amplifier that converts the electric current signal into a voltage signal;a differential amplifier that converts the voltage signal into a differential signal, by performing differential amplification of a difference between the voltage signal and a threshold voltage; anda control section that repeatedly executes offset cancellation processing, the offset cancellation processing including threshold voltage change processing in which the threshold voltage is changed such that an offset voltage of the differential signal is reduced,the offset cancellation processing having two execution modes which are different from each other in an amount of change in the threshold voltage during the threshold voltage change processing, the two execution modes including a first execution mode in which the amount of change in the threshold voltage is greater and a second execution mode in which the amount of change in the threshold voltage is smaller, andat a point at which a sign of the offset voltage inverts, or at a point at which a level of the offset voltage becomes less than a tolerance, the control section switching the first execution mode to the second execution mode. 8. The optical receiver according to claim 7, wherein: the control section writes a value of the threshold voltage to a nonvolatile memory either at the time when operation of the control section ends or periodically during the operation of the control section; andat the time when the operation of the control section commences next, the control section reads out, from the nonvolatile memory, the value of the threshold voltage, and uses, as an initial value for the offset cancellation processing, the value of the threshold voltage that has been read out. 9. The optical receiver according to claim 7, further comprising a variable voltage source that generates the threshold voltage, the control section changing the threshold voltage by controlling the variable voltage source. 10. An active optical cable comprising an optical receiver according to claim 7. 11. A control method for an optical receiver, the optical receiver including:a photodetector element that converts an optical signal into an electric current signal;a transimpedance amplifier that converts the electric current signal into a voltage signal;a differential amplifier that converts the voltage signal into a differential signal, by performing differential amplification of a difference between the voltage signal and a threshold voltage; anda control section that repeatedly executes offset cancellation processing, the offset cancellation processing including threshold voltage change processing in which the threshold voltage is changed such that an offset voltage of the differential signal is reduced,the control method comprising the step of:at a point at which a sign of the offset voltage inverts, or at a point at which a level of the offset voltage becomes less than a tolerance, reducing a frequency at which the offset cancellation processing is executed. 12. A control method for an optical receiver, the optical receiver including:a photodetector element that converts an optical signal into an electric current signal;a transimpedance amplifier that converts the electric current signal into a voltage signal;a differential amplifier that converts the voltage signal into a differential signal, by performing differential amplification of a difference between the voltage signal and a threshold voltage; anda control section that repeatedly executes offset cancellation processing, the offset cancellation processing including threshold voltage change processing in which the threshold voltage is changed such that an offset voltage of the differential signal is reduced,the offset cancellation processing having two execution modes which are different from each other in an amount of change in the threshold voltage during the threshold voltage change processing, the two execution modes including a first execution mode in which the amount of change in the threshold voltage is greater and a second execution mode in which the amount of change in the threshold voltage is smaller,the control method comprising the step of:at a point at which a sign of the offset voltage inverts, or at a point at which a level of the offset voltage becomes less than a tolerance, switching the first execution mode to the second execution mode.
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