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. 21, 2004
Filed:
Jun. 08, 2001
Terence J. Murphy, Plano, TX (US);
Keith W. Malang, Longmount, CO (US);
Larry G. Hutsell, Loveland, CO (US);
Doug Martin, Freemont, CA (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A piezo actuator drive circuit ( ) adapted to operate in both a charge mode and a voltage mode. A low frequency compensation loop ( ) is formed from a piezo actuator output (OUT6XP) of a driver ( ) to the input thereof. The resulting closed loop system produces charge mode operation within a bandpass that can be tuned for desired operation. Below the bandpass turn on frequency (F ) the closed loop system restores the piezo output (OUT6XP) to a defined DC voltage and compensates for any wandering effects, such as DC current mismatches in the closed loop configuration, such that the piezo output is centered around the desired DC operating point. The circuit is further provided with a DC restore feature in combination with the feedback which allows for a low frequency DC coupled path and thus allows for the DC positioning of the piezo in the charge mode to be changed. The DC restoring amplifier is used to compensate for offsets in the amplifier chain. The DC restore amplifier ensures the overall circuit is balanced and that the charge mode operation is maintained. The circuit is particularly adapted to drive a varying number of multiple piezo actuators.