发明名称 |
Control loop circuit and method therefor |
摘要 |
In an optical communications system, it is necessary to control the extinction ratio of a laser device (192) of an optical transmission unit. The laser device (192) is typically used to transmit a signal that can be approximated by a pseudo-random bit stream. The bit stream is monitored by collecting light from a back facet of the laser device (192) using a photodiode (194) in a control loop. Due to band limiting effects of the photodiode (194) and parasitic circuit track capacitances, a feedback signal generated by the photodiode (194) becomes distorted, leading to difficulties in controlling the extinction ratio. The present invention therefore provides an apparatus that simulates a signal generated by the photodiode (194) and subsequent processing of the photodiode signal. The simulated signal and the processed photodiode signal are compared so as to generate a control signal for controlling modulation amplitude of the laser device (192) and hence the extinction ratio.
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申请公布号 |
US6829267(B2) |
申请公布日期 |
2004.12.07 |
申请号 |
US20020232374 |
申请日期 |
2002.09.03 |
申请人 |
AGILENT TECHNOLOGIES INC. |
发明人 |
VAUGHAN BARRY JOHN;EVERETT KEITH;RITCHIE CHARLES GRAEME |
分类号 |
H04B10/155;H04B10/50;(IPC1-7):H01B3/00 |
主分类号 |
H04B10/155 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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