Pulse oximeter with improved DC and low frequency rejection
US6381479B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 17, 1999 |
| Grant date | Apr 30, 2002 |
| Priority date | — |
| Expiry date | Dec 17, 2019 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B5/145
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A system for providing an improved DC and low frequency signal rejection in a photoplethysmographic measurement instrument is disclosed. The system is used in a measurement instrument which includes at least two signal sources (106, 108) for transmitting light signals at least at two wavelengths through a tissue of a test subject and a detector (112) for converting light signals transmitted through the tissue into a detector output signal. The system includes a DC restoration (114) which removes DC and low frequency signal components from the detector output signal prior to amplification thereof so as to avoid saturating amplified output signal with the low frequency signal component. The DC restoration (114) is configured to continuously remove low frequency signal component from the detector signal during dark intervals when the signal sources are deactivated, as well as during light intervals when one of the signal sources is activated. In one embodiment, the DC restoration is embodied in the form of a DC restoration circuit (200) which comprises a transimpedance amplifier (204, 206) which receives the detector output signal and produces an amplifier output signal (222) and an i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.