Oximeter with nulled op-amp current feedback
US6720734B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 8, 2002 |
| Grant date | Apr 13, 2004 |
| Priority date | — |
| Expiry date | Aug 8, 2022 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/7225
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A method of producing a diode drive current in an oximeter includes sensing at least a part of a current passing through the diode and converting the sensed current to a sensed voltage, inputting the sensed voltage to a feedback amplifier for stabilizing the current passing through the diode, and eliminating an offset voltage across inputs of the feedback amplifier. A pulse oximeter includes a diode for emitting light flashes, a feedback amplifier having inputs, a feedback capacitor, and an output, the feedback amplifier stabilizing a current passing through the diode, a nulling amplifier having inputs, a nulling capacitor, and an output, the nulling amplifier charging and discharging the feedback capacitor until the inputs of the feedback amplifier are at a same voltage. The operation may include synchronizing an elimination of input offset voltages of the feedback and nulling amplifiers with on or off state of diode current.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.