Ambient light compensation circuit for analyte measurement systems

摘要

A blood analyte measurement system is configured to receive a test strip. An LED proximate to the test strip is used to illuminate the test strip and, in conjunction with a photodiode, to determine its type. A compensation circuit of the measurement system insures that ambient light does not cause interference with the LED illumination to prevent saturation of the photodiode.

主权项

1. An ambient light compensation circuit comprising:
a first gain stage comprising:
a voltage source;a power supply;a photodiode connected to the voltage source;a first operational amplifier connected to the photodiode and to the power supply, the first operational amplifier having a first gain stage output terminal;a first voltage divider connected to the voltage source and the first operational amplifier for providing a first reference voltage to the first operational amplifier, the voltage divider comprising a first pair of resistors; and a coupling capacitor coupled in series to the first gain stage output terminal and to a second gain stage, the coupling capacitor for transmitting a voltage pulse from the first gain stage output terminal to the second gain stage,wherein the second gain stage comprises:
a second operational amplifier connected to the coupling capacitor through a coupling resistor and to the power supply, the second operational amplifier having a compensation circuit output terminal; a second voltage divider connected to the voltage source and to the second operational amplifier for providing a second reference voltage to the second operational amplifier, the second voltage divider comprising a second pair of resistors; and wherein the compensation circuit output terminal is connected to the coupling resistor through a second stage gain control resistor for compensating a DC voltage of the coupling capacitor, the DC voltage generated by ambient light impacting the photodiode.