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:
Feb. 11, 2003
Filed:
Oct. 18, 1999
Scott L. Broutin, Kutztown, PA (US);
James Kevin Plourde, Allentown, PA (US);
John William Stayt, Jr., Schnecksville, PA (US);
Agere Systems Inc., Miami Lakes, FL (US);
Abstract
A circuit for increasing the signal-to-noise ratio in an optical communication system and for stabilizing a laser wavelength. The circuit includes an impedance element disposed in parallel relation with the input capacitance of the circuit to increase the input capacitance for filtering out noise in the circuit to thereby achieve a high signal-to-noise ratio. The bandwidth of the noise signal is kept low to achieve high signal-to-noise ratios and efficient wavelength stabilization. By operating at low bandwidths, the input capacitance of the circuit does not dominate the shunt voltage and associated current due to the noise; rather, a feedback resistance associated with an operational amplifier dominates the magnitude of the noise current. Thus, the input capacitance can be increased without increasing noise current, which effectively filters the noise from the total current in the circuit and advantageously insures that the bandwidth of the noise is low and the signal-to-noise ratio of the circuit remains high.