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:
Aug. 17, 2004
Filed:
Dec. 11, 2003
Gilles P. Denoyer, San Jose, CA (US);
Daniel Case, Gilroy, CA (US);
Finisar Corporation, Sunnyvale, CA (US);
Abstract
A wide dynamic range transimpedance amplifier with a low cut off frequency at high optical power. An automatic transimpedance gain control and DC cancellation control feedback circuit includes variable impedance circuitry. An emitter terminal of a first pnp transistor is connected to the input of the transimpedance amplifier. The impedance seen at the emitter terminal changes according to the average value of the input current. Open loop gain of the feedback loop including the first pnp transistor is not dependent on the average input current as the input current increases. A base terminal of the first pnp transistor is connected to a base terminal of second pnp transistor. Emitter size of the second pnp transistor is some factor N smaller than emitter size of the first pnp transistor. N can be configured to adjust the gain control and low corner frequency variation with input power.