Demodulation in a contact hearing system
In embodiments of the invention, the present invention is directed to a contact hearing system including: a transmit coil positioned in an ear tip wherein the transmit coil includes an electrical coil wound on a ferrite core; a receive coil positioned on a contact hearing device wherein the receive coil includes an electrical coil without a core; a load connected to the receive coil; and a demodulation circuit connected to the receive coil and the load wherein the demodulation circuit includes a voltage doubler and a peak detector.
1. A contact hearing system comprising:
a transmit coil positioned in an ear tip, wherein the transmit coil comprises an electrical coil wound on a ferrite core;
a receive coil positioned on a contact hearing device wherein the receive coil comprises an electrical coil without a core;
a load connected to the receive coil; and
a demodulation circuit connected to the receive coil and the load, wherein the demodulation circuit comprises a voltage doubler and a peak detector, and wherein the receive coil passes a signal to the demodulation circuit having reduced intermodulation distortion (IMD) based on a passband associated with the receive coil being centered at a frequency greater than a carrier frequency of a signal transmitted from the transmit coil to the receive coil;
wherein the load is a microactuator for directly vibrating an eardrum of the user to produce a perception of sound by the user.
2. A contact hearing system according to claim 1 , wherein the demodulation circuit is connected to the load at a motor node.
3. A contact hearing system according to claim 2 , wherein a tuning capacitor is connected across the receive coil.
4. A contact hearing system according to claim 3 , wherein the voltage doubler comprises a series capacitor connected to a first diode.
5. A contact hearing system according to claim 4 , wherein the series capacitor is connected between a first side of the receive coil and a cathode diode.
6. A contact hearing system according to claim 5 , wherein the cathode of the first diode is connected to a second side of the receive coil.
7. A contact hearing system according to claim 1 , wherein the peak detector is connected between an output of the voltage doubler and the load.
8. A contact hearing system according to claim 7 , wherein the peak detector comprises a second diode and a smoothing capacitor.
9. A contact hearing system according to claim 8 , wherein an anode of the second diode is connected to the voltage doubler.
10. A contact hearing system according to claim 9 , wherein a cathode of the first diode is connected to an anode of the second diode.
11. A contact hearing system according to claim 9 , wherein a cathode of the second diode is connected to a first side of the smoothing capacitor.
12. A contact hearing system according to claim 10 , wherein the cathode of the second diode and the first side of the smoothing capacitor is connected to a first side of the load.
13. A contact hearing system according to claim 12 , wherein a second side of the load is connected to a second side of the smoothing capacitor.
14. A contact hearing system according to claim 4 , wherein the first diode is a Schottky diode.
15. A contact hearing system according to claim 8 , wherein the second diode is a Schottky diode.
16. A contact hearing system according to claim 1 , wherein the load is a balanced armature microactuator.
17. A contact hearing system according to claim 1 , further comprising an output filter connected to the demodulation circuit and the load.
18. A contact hearing system according to claim 17 , wherein the output filter comprises an LC output filter.
19. A contact hearing system according to claim 17 , wherein the output filter is connected to the peak detector of the demodulation circuit and the load.
20. A contact hearing system comprising:
a transmit coil positioned in an ear tip, wherein the transmit coil comprises an electrical coil wound on a ferrite core;
a receive coil positioned on a contact hearing device wherein the receive coil comprises an electrical coil without a core;
a load connected to the receive coil; and
a demodulation circuit connected to the receive coil and the load, wherein the demodulation circuit comprises a voltage doubler and a peak detector,
wherein the receive coil passes a signal to the demodulation circuit having reduced intermodulation distortion (IMD) based on a passband associated with the receive coil being centered at a frequency greater than a carrier frequency of a signal transmitted from the transmit coil to the receive coil,
wherein the voltage doubler comprises a series capacitor connected to a first diode,
wherein the peak detector is connected between an output of the voltage doubler and the load,
wherein the peak detector comprises a second diode and a smoothing capacitor,
wherein the cathode of the second diode and the first side of the smoothing capacitor is connected to a first side of the load,
wherein a second side of the load is connected to a second side of the smoothing capacitor, and
wherein the load is a balanced armature microactuator for directly vibrating an eardrum of the user to produce a perception of sound by the user.