The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 04, 1993
Filed:
Apr. 10, 1992
Ming-Lai Kao, Lower Macungie Township, Lehigh County, PA (US);
Yong-Kwan Park, Lower Macungie Township, Lehigh County, PA (US);
AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
An externally modulated laser-based transmitter is disclosed which utilizes an automatic bias control (ABC) circuit to maintain the bias voltage applied to the external modulator at a predetermined level required to provide the necessary separation between logic levels. The ABC circuit generates a dither signal and functions to digitally compare the phase of the dither signal to the phase of the optical signal produced by the external modulator. A phase comparator (e.g., D-type flip-flop) is used to monitor any drift in the optimum bias point of the modulator and generate an output correction signal by continuously adjusting the level of the DC bias voltage applied to the external modulator.