초록 ▼

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 parti

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.

대표청구항 ▼

[ What is claimed is:] [1.] A low power current-to-frequency (I-to-F) converter circuit for use within an implantable device, comprising:an amplifier having two input terminals and an output terminal, the amplifier comprising means for differentially amplifying an electrical signal applied between i

[ What is claimed is:] [1.] A low power current-to-frequency (I-to-F) converter circuit for use within an implantable device, comprising:an amplifier having two input terminals and an output terminal, the amplifier comprising means for differentially amplifying an electrical signal applied between its two input terminals to provide an amplified output signal V.sub.OUT appearing on its output terminal;a first capacitor electrically connected to at least one of the input terminals of the amplifier;a voltage controlled oscillator (VCO) circuit having a voltage-control input terminal and a VCO output terminal, the voltage-control input terminal being connected to the output terminal of the amplifier, the VCO including means for generating a frequency output signal F.sub.OUT having a frequency that varies as a function of the magnitude of a voltage applied to the voltage-control input; anda charge-pump circuit coupled to the first capacitor that pumps a discrete charge off of said first capacitor under control of the frequency output signal F.sub.OUT generated by the VCO.