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:
Sep. 03, 2002
Filed:
Aug. 22, 2001
Haoran Zhang, Tucson, AZ (US);
Gregory S. Waterfall, Tucson, AZ (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A charge pump circuit is provided for reducing the voltage ripple and EMI associated with prior art circuits. The charge pump circuit is configured with at least one current source for suitably controlling the charging and/or discharging current in the charge pump capacitors the currents of the current sources are determined by the load current requirements, rather than the on-resistance of any switches or the ESR of any capacitors, thus allowing a significant reduction of the peak current drawn from the power supply as well as the peak current injected into the output reservoir capacitor. The charge pump circuit can be configured with a current source in series with the input supply voltage to control the total current in the charge pump. In addition, the charge pump circuit can be configured with current limited switches for controlling the total current. For example, current sources can be suitably configured to replace one or more switches in the charge pump circuit to effectively control the total current in the charge pump circuit. By feeding the charge pump capacitors with switched current sources, the voltage across the current sources can be suitably limited to the supply voltage or the output voltage. In addition, the current sources can operate as resistor devices with adjustable impedances, and be configured to suitably reduce or eliminate the excessive supply voltage across the current sources. Further, the switched current sources can comprise various current mirror configurations. As a result, the requirement for the breakdown voltage can be significantly reduced. In addition, through use of a low voltage process, the cost and packaging size can be suitably reduced.