Blood constituent measuring device and method
Condensed oximeter system with noise reduction software Patent #: 5351685
ApplicationNo. 465858 filed on 12/17/1999
US Classes:600/322, Determining blood constituent600/336Detects constituents while excluding components (e.g., noise)
ExaminersPrimary: Winakur, Eric F.
Attorney, Agent or Firm
International ClassA61B 005/00
AbstractThe pulse oximeter instrument of the present invention includes switched gain, channel rotation and bootstrap amplification features. In one embodiment, a time-division multiplexed gain circuit is provided in receiver circuitry and is equipped with a switched gain amplifier to faciliate the use of a fixed light source drive and otherwise improve the signal processing characteristics of the instrument. Signal processing is further enhanced via use of a transimpedance amplifier and bootstrap amplifier interconnected across one or more photodiodes. The apparatus time division multiplexes (TDM) the optical input channels to customize the gain response of the apparatus to the variable characteristics of each input channel. Thus, the channel-specific error sources are determined and precisely eliminated from the input data. The channels may also be rotated in subsequent signal conditioning that entails demultiplexing/multiplexing.