SWITCHED CAPACITOR APPARATUS PROVIDING INTEGRATION OF AN INPUT SIGNAL

• US 20090309645A1
• Filed: 06/12/2009
• Published: 12/17/2009
• Est. Priority Date: 06/13/2008
• Status: Abandoned Application

• Current Assignee: Nonin Medical Incorporated
• Original Assignee: Nonin Medical Incorporated
• Inventors: Schilling, Josh D., Isaacson, Philip O.
• Application Number:
  US12/483,428
• Publication Number:
  US 20090309645A1
• Time in Patent Office: Days
• US Class Current: 327/337
• CPC Class Codes: G06G 7/186 using an operational amplifier comprising a capacitor or a resistor in the feedback loop

Abstract

An apparatus includes an operational amplifier, a switched capacitor network, an optical sensor, and a clock. The switched capacitor network is coupled to an input terminal of the operational amplifier and coupled to an output terminal of the operational amplifier. The optical sensor includes a sensor output coupled to the switched capacitor network. The clock is coupled to at least one switch of the switched capacitor network. The clock is configured to activate the at least one switch to provide an integrated output at the output terminal corresponding to the sensor output.

Claims

1. An apparatus comprising:

an operational amplifier;

a switched capacitor network coupled to an input terminal of the operational amplifier and coupled to an output terminal of the operational amplifier;

an optical sensor having a sensor output coupled to the switched capacitor network; and

a clock coupled to at least one switch of the switched capacitor network, the clock configured to activate the at least one switch to provide an integrated output at the output terminal corresponding to the sensor output.

2. The apparatus of claim 1 wherein the switched capacitor network includes at least one capacitor coupled to a switch.

3. The apparatus of claim 1 wherein the sensor output includes a pulse train.

4. The apparatus of claim 1 wherein the sensor output includes a sensor signal corresponding to a selected frequency of light.

5. The apparatus of claim 1 wherein the sensor output includes a sensor signal corresponding to a plurality of frequencies of light.

6. The apparatus of claim 1 wherein the sensor output corresponds to radiation in at least one of a red range and a near infrared range.

7. The apparatus of claim 1 wherein the clock includes a reset clock signal coupled to a reset switch of the switched capacitor network.

8. The apparatus of claim 7 wherein the reset switch is coupled in parallel with a feedback capacitor.

9. The apparatus of claim 8 wherein the feedback capacitor is coupled between the input terminal and the output terminal.

10. The apparatus of claim 1 wherein the clock includes a first clock signal and a second clock signal in which the first clock signal and the second clock signal are non-overlapping.

11. The apparatus of claim 10 wherein the first clock signal is coupled to a first input switch of the switched capacitor network and the second clock signal is coupled to a second input switch of the switched capacitor network.

12. A system comprising:

an integrating operational amplifier having a switched capacitor network coupled to an amplifier input and coupled to an amplifier output;

an optical sensor having a sensor output coupled to the switched capacitor network;

a clock coupled to the switched capacitor network, the clock configured to activate at least one switch of the switched capacitor network to provide an integrated output at the amplifier output corresponding to the sensor output; and

an output circuit coupled to the amplifier output, the output circuit including a display.

13. The system of claim 12 wherein the switched capacitor network includes a plurality of switches, each of which is coupled to the clock.

14. The system of claim 12 wherein the sensor output includes a signal corresponding to light of at least one of a red range and a near infrared range.

15. The system of claim 12 wherein the clock includes a first clock signal coupled to a reset switch of the switched capacitor network.

16. The system of claim 15 wherein the clock includes a first square wave signal in phase with the first clock signal.

17. The system of claim 16 wherein the clock includes a second square wave signal in phase with the first square wave signal.

18. The system of claim 17 wherein the second square wave signal is non-overlapping with the first square wave signal.

19. A method comprising:

receiving a pulsed signal from an optical sensor based on a tissue;

integrating the pulsed signal using a switched capacitor network coupled to an operational amplifier; and

generating an output based on the integrated pulsed signal, the output corresponding to a physiological parameter for the tissue.

20. The method of claim 19 wherein receiving the pulsed signal includes receiving a signal corresponding to light of at least one of a red range and an infrared range.

21. The method of claim 19 wherein integrating the pulsed signal includes actuating at least one switch of the switched capacitor network using a clock signal.

22. The method of claim 19 wherein generating the output includes displaying a measure of oximetry.