Claims
- 1. A method of stabilizing the driving of a current through a diode of an oximeter, comprising:
connecting a feedback-controlled device to the diode, the feedback-controlled device comprising a feedback loop; sensing a current being input to the feedback loop; and adding phase lead to the sensed current with a ferrite, the ferrite being disposed in series with the sensed current.
- 2. A method of stabilizing the driving of a current through a diode of an oximeter, comprising:
sensing at least part of the current through the diode, using a current sense element; controlling a connecting of the current through the diode, the controlling being based on current sensed by the current sense element; and stabilizing the controlling with a ferrite, the ferrite being disposed in series with the current sense element, an inductance value of the ferrite being set to counteract a phase lag imposed on apparatus performing the controlling.
- 3. A method of stabilizing the driving a current through a diode of an oximeter as claimed in claim 2, further comprising damping the current sensed by the current sense element.
- 4. A method of stabilizing the driving a current through a diode of an oximeter as claimed in claim 3, wherein the damping comprises adding phase lead to the current sensed by the current sense element.
- 5. A method of driving a current through a diode of an oximeter, comprising:
sensing a current of a signal being input to a feedback type amplifier; adding phase lead to the signal being input to the feedback type amplifier; and driving a diode with at least part of the signal having added phase lead.
- 6. A method according to claim 5, wherein the feedback type amplifier comprises a current source having a current-limiting element.
- 7. A method of driving a current through a diode of an oximeter, comprising:
driving a current through the diode by connecting the current to the diode; controlling the connecting using a feedback type amplifier, the feedback type amplifier having a current source that uses a current-limiting element; and adding phase lead to a current passing through the current-limiting element.
- 8. A method of driving a current through a diode of an oximeter as claimed in claim 7, further comprising damping the current passing through the current-limiting element.
- 9. A method of driving a current through a diode of an oximeter as claimed in claim 7, further comprising isolating a feedback of the feedback type amplifier when the current to the diode is in an off state.
- 10. A method of driving a current through a diode of an oximeter as claimed in claim 7, wherein the connecting is performed by a transistor.
- 11. An oximeter diode-driving device, comprising:
a diode; a transistor operative to controllably connect current to the diode; a current sensing element that senses at least part of the current; a feedback amplifier operative to control the connecting of current by the transistor according to the current sensed by the current sensing element; and an inductor disposed in series with the current sensing element.
- 12. An oximeter diode-driving device according to claim 11, further comprising a cable connecting the diode to the transistor, wherein an inductance value of the inductor is set to counteract a phase lag caused by at least one of reactance of the cable and capacitance across the transistor.
- 13. An oximeter diode-driving device according to claim 12, wherein an inductance value of the inductor is set to counteract a phase lag caused by the combined sluggishness of the transistor, feedback amplifier, and cable.
- 14. An oximeter diode-driving device according to claim 11, further comprising:
a feedback capacitor disposed between the transistor and an inverting input of the feedback amplifier; and a feedback element disposed in parallel with the feedback capacitor.
- 15. An oximeter diode-driving device according to claim 14, wherein a capacitance value of the feedback capacitor and a resistance value of the feedback element are set to define an on/off time constant for the feedback amplifier.
- 16. An oximeter diode-driving device according to claim 15, wherein the capacitance value of the feedback capacitor is set to counteract a phase lag caused by an input capacitance of the feedback amplifier.
- 17. An oximeter diode-driving device according to claim 11, further comprising a damping element disposed in parallel with the inductor.
- 18. An oximeter diode-driving device according to claim 17, wherein a resistance value of the damping element is set based on lowering a Q of the inductor by a predetermined amount.
- 19. An oximeter diode-driving device according to claim 11, wherein the diode is a laser diode.
- 20. An oximeter diode-driving device according to claim 11, wherein the diode is a light-emitting diode.
- 21. An oximeter diode-driving device according to claim 11, wherein the inductor is a ferrite bead.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application incorporates by reference U.S. patent application Ser. No. [SN not yet assigned] titled “Feedback-Controlled LED Switching”, and U.S. patent application Ser. No. [SN not yet assigned] titled “Nulled Op-Amp Current Feedback”, both filed [date when filed].