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. 12, 2013
Filed:
May. 10, 2010
Zutao Liu, ZiZhu Science Park, CN;
Kun Cheng, ZiZhu Science Park, CN;
Jianbo Sun, ZiZhu Science Park, CN;
Gang Shi, ZiZhu Science Park, CN;
Zutao Liu, ZiZhu Science Park, CN;
Kun Cheng, ZiZhu Science Park, CN;
Jianbo Sun, ZiZhu Science Park, CN;
Gang Shi, ZiZhu Science Park, CN;
Other;
Abstract
The present invention relates to a parallel light emitting diode ('LED') drive circuit and provides a drive circuit configured to drive a parallel array of LEDs. The drive circuit comprises: a switching control signal generator, a plurality of switches, a plurality of sampling resistors, and a plurality of chopper amplifiers. Each switch is coupled to a respective LED in the LED array. Each chopper operational amplifier configured to receive a reference voltage and a switching control signal generated by the switching control signal generator and generate an input offset voltage. Each chopper operational amplifier includes a differential amplifier including an input transistor pair and a current mirror transistor pair, of which the electrical positions can be reserved when the switching control signal is switched between a first state and a second state, wherein the offset voltage, which causes the lightness mismatching in a parallel LED circuit, can be cancelled.