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:
Jun. 29, 1999
Filed:
Sep. 12, 1997
John C Gord, Venice, CA (US);
Alfred E. Mann Foundation, Sylamr, CA (US);
Abstract
A low power current-to-frequency converter circuit provides an output frequency signal F.sub.OUT having a frequency that varies as a function of a low level analog input current signal. The analog input current signal is typically generated by an implantable sensor element, designed to sense a particular substance or parameter within body tissue or fluids to which the sensor is exposed, with the magnitude of the analog signal providing a measure of the sensed substance or parameter. Conversion of the low level analog current to the output frequency signal facilitates transmission of the data signal over a shared data bus and other digital processing of the data signal. The current-to-frequency converter circuit is fabricated from low power FET-based integrated circuits, typically realized on a single integrated circuit chip, and includes an operational amplifier having its positive input terminal connected to a storage capacitor that is charged by the analog input current signal, a voltage-controlled oscillator driven by the charge (voltage) on the storage capacitor that produces the output frequency signal, and a charge pump circuit that pumps a discrete amount of charge off of the storage capacitor during each cycle of the output frequency signal.