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:
Mar. 05, 1991
Filed:
Dec. 01, 1989
Herman A Kruse, Winder, GA (US);
Scientific Atlanta, Inc., Atlanta, GA (US);
Abstract
A transimpedance receiver for broad band optical signals, such as carry multichannel CATV signals or broad band data over an optical fiber which may vary in length (e.g. from 2 km to 20 km) such that the optical power at a photodetector of the receiver may vary widely depending upon where the receiver, and is installed in the fiber optic distribution system utilizes a broad band device, preferably a GASFET, the internal capacitance and gain of which enables amplification over the broad band frequency range without oscillation. Different values of transimpedance for converting the current signal from the photodetector into an output voltage at the output (the drain) of the device which is in a range within which the device is linear, and does not introduce distortion into the signal, is obtained by connecting, between the output and the input of the device, a feedback resistor selected from a group consisting of resistors of different value each dependent upon the optical power of the optical signal applied to the photodetector. The output voltage is coupled to an electrical transmission line which may be a low impedance coaxial line using a buffer amplifier incorporating a device of the same type as used in the transimpedance amplifier which has connected thereto networks for controlling the spectral response of the receiver so that it remains essentially flat over the broad band frequency range.