Claims
- 1. 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.
- 2. An oximeter diode-driving device according to claim 1, wherein the diode is a laser diode.
- 3. An oximeter diode-driving device according to claim 1, wherein the diode is a light-emitting diode.
- 4. An oximeter diode-driving device according to claim 1, wherein the inductor is a ferrite bead.
- 5. An oximeter diode-driving device according to claim 1, 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.
- 6. An oximeter diode-driving device according to claim 5, 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.
- 7. An oximeter diode-driving device according to claim 1, further comprising a damping element disposed in parallel with the inductor.
- 8. An oximeter diode-driving device according to claim 7, wherein a resistance value of the damping element is set based on lowering a Q of the inductor by a predetermined amount.
- 9. An oximeter diode-driving device according to claim 1, 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.
- 10. An oximeter diode-driving device according to claim 9, 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.
- 11. An oximeter diode-driving device according to claim 10, wherein the capacitance value of the feedback capacitor is set to counteract a phase lag caused by an input capacitance of the feedback amplifier.
CROSS REFERENCE TO RELATED APPLICATIONS
This application incorporates by reference U.S. patent application Ser. No. 10/251,878 titled “Feedback-Controlled LED Switching”, and U.S. patent application Ser. No. 10/215,935 titled “Nulled Op-Amp Current Feedback”, both filed Aug. 8, 2002.
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