OXIMETER WITH NULLED OP-AMP CURRENT FEEDBACK
First Claim
1. A method of producing a diode drive current in an oximeter, comprising:
- 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.
1 Assignment
0 Petitions
Accused Products
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.
-
Citations
30 Claims
-
1. A method of producing a diode drive current in an oximeter, comprising:
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A pulse oximeter that converts pulses into light flashes, comprising:
-
a diode for emitting the light flashes;
a feedback amplifier having inputs, a feedback capacitor, and an output, the feedback amplifier being operative to stabilize a current passing through the diode; and
a nulling amplifier having inputs, a nulling capacitor, and an output, the nulling amplifier being operative to charge and discharge the feedback capacitor until the inputs of the feedback amplifier are at a same voltage. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
-
-
28. A pulse oximetry device that converts pulses into light flashes, comprising:
-
a plurality of diodes for emitting the light flashes;
a plurality of current sense resistors corresponding to the plurality of diodes, for sensing at least a part of a current being supplied to each respective diode of the oximeter;
at least one feedback amplifier having inputs, a feedback capacitor, and an output, the feedback amplifier being operative to stabilize at least one current passing through the plurality of diodes; and
at least one nulling amplifier having inputs, a nulling capacitor, and an output, the at least one nulling amplifier being operative to charge and discharge at least one feedback capacitor until the respective inputs of the at least one feedback amplifier are at a same voltage. - View Dependent Claims (29)
-
-
30. A method of producing a diode drive current in an oximeter, comprising nulling an operational amplifier (op-amp) disposed in the feedback path of a diode drive circuit.
Specification