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:
Oct. 10, 2000
Filed:
Aug. 14, 1998
Fridolin L Bosch, Bethlehem, PA (US);
Gregory C Salvador, Wernersville, PA (US);
Lucent Technologies, Inc., Murray Hill, NJ (US);
Abstract
A digital driver circuit with increased maximum output voltage amplitude and therefore also increased maximum current amplitude for constant power supply voltages is provided. A current sensing resistor replaces the conventional current source transistor in the output stage of the driver circuit. In addition, the output current control circuit is applied to an earlier stage of the driver. An automatic output current control scheme is created which keeps the voltage across the current sensing resistor equal to a DC reference and therefore maintains the output current or voltage amplitude by actively level shifting the DATA and DATA drive signals for the output stage to the correct level. This eliminates the necessity to incorporate a voltage safety margin and simultaneously increases the maximum available output voltage amplitude. Therefore, by utilizing the current sensing resistor and by moving the output amplitude control circuit to an earlier stage of the driver circuit, the driver circuit of the present invention provides increased output voltage and current amplitudes to drive modulated devices. In another embodiment, the automatic output amplitude control scheme is created by keeping the voltage across the current sensing resistor equal to a Mark-Bar reference signal corresponding to input data.