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:
Apr. 04, 1989
Filed:
Aug. 28, 1987
Vicente V Cavanna, Loomis, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A driver for an electro-optical transducer, such as a light-emitting diode (LED) is disclosed which shapes current pulses so as to contain 'spikes' during turn-on and turn-off in order to quickly charge and discharge the junction and stray capacitances of the LED. Degeneration resistors interconnect the emitters of switching transistors used in a differential amplifier supplying the current to the LED and in a differential amplifier supplying a 'peaking' current to the switching amplifier. A capacitor couples the amplifiers to conduct the additional current to the LED when it is initially turned on and charges the cathode of the LED. The emitter degeneration resistors couple the amplifiers to current sources and allow the amplifiers to be driven by emitter-coupled logic (ECL) gates without ringing. The resistors also linearize the transfer functions of the amplifiers so that the voltage swing of the ECL driver does not overly turn-off the transistors within the amplifiers, thereby improving response time.