Claims
- 1. A digital hearing aid comprising:
at least one microphone; a first preamplifier operatively coupled to the at least one microphone; a second preamplifier operatively coupled to the at least one microphone; an analog-to-digital converter; and a switch operatively coupled to first preamplifier, the second preamplifier and the analog-to-digital converter, that switches between an output generated by the first preamplifier and an output generated by the second preamplifier for input to the analog-to-digital converter.
- 2. The digital hearing aid of claim 1 wherein the first preamplifier comprises a low amplitude preamplifier and the second preamplifier comprises a high amplitude preamplifier.
- 3. The digital hearing aid of claim 2 wherein the first preamplifier is selected by the switch for low level signals generated by the microphone and the second preamplifier is selected by the switch for high level signals generated by the microphone.
- 4. The digital hearing aid of claim 1 further comprising a digital signal processor that applies a first gain correction when the first preamplifier is selected by the switch, and a second gain correction when the second preamplifier is selected by the switch.
- 5. A digital hearing aid comprising:
a first analog-to-digital converter; a second analog-to-digital converter; and a single clock that provides a sampling trigger for both the first and second analog-to-digital converters.
- 6. The digital hearing aid of claim 5 wherein the first analog-to-digital converter is a low amplitude analog-to-digital converter, and the second analog-to-digital converter is a high amplitude analog-to-digital converter.
- 7. The digital hearing aid of claim 5 further comprising a digital signal processor that uses a first bit string from the first analog-to-digital converter when an input is below an amplitude level, and a second bit string from the second analog-to-digital converter when the input is above an amplitude level.
- 8. The digital hearing aid of claim 7 comprising a single amplitude level.
- 9. The digital hearing aid of claim 5 further comprising a digital signal processor that uses a first bit string from the first analog-to-digital converter when an input is below a first amplitude level, a second bit string from the second analog-to-digital converter when the input is above a second amplitude level, and a combination of the first and second bit strings when the input is between the first and second amplitude levels.
- 10. A digital hearing aid comprising:
a first analog-to-digital converter; a second analog-to-digital converter; and a digital signal processor that uses a first bit string from the first analog-to-digital converter when an input is below an amplitude level, and a second bit string from the second analog-to-digital converter when the input is above an amplitude level.
- 11. The digital hearing aid of claim 10 wherein the first analog-to-digital converter is a low-amplitude analog-to-digital converter, and the second analog-to-digital converter is a high-amplitude analog-to-digital converter.
- 12. The digital hearing aid of claim 11 comprising a single amplitude level.
- 13. The digital hearing aid of claim 10 wherein the digital signal processor uses the first bit string from the first analog-to-digital converter when the input is below a first amplitude level, the second bit string from the second analog-to-digital converter when the input is above a second amplitude level, and a combination of the first and second bit strings when the input is between the first and second amplitude levels.
- 14. The digital hearing aid of claim 10 further comprising a single clock that provides a sampling trigger for both the first and the second analog-to-digital converters.
- 15. A method of operating a digital hearing aid, the method comprising:
converting sound into an electrical signal; amplifying the electrical signal to generate a first amplified signal; amplifying the electrical signal to generate a second amplified signal; selecting one of the first amplified signal and the second amplified signal based on the electrical signal; and converting the selected signal to a digital value.
- 16. The method of claim 15 further comprising applying a first gain correction when the first amplified signal is selected, and a second gain correction when the second amplified signal is selected.
- 17. A method of operating a digital hearing aid, the method comprising:
generating a first digital signal using a first analog-to-digital converter; generating a second digital signal using a second analog-to-digital converter; and triggering the sample conversion of both the first analog-to-digital converter and the sample conversion of the second analog-to-digital converter from a single clock.
- 18. The method of claim 17 wherein the first analog-to-digital converter is a low amplitude analog-to-digital converter, and the second analog-to-digital converter is a high amplitude analog-to-digital converter.
- 19. The method of claim 17, the method further comprising processing a first bit string from the first analog-to-digital converter when an input is below an amplitude level, and processing a second bit string from the second analog-to-digital converter when the input is above an amplitude level.
- 20. The method of claim 19 wherein the amplitude level is a single amplitude level.
- 21. The method of claim 17, the method further comprising processing a first bit string from the first analog-to-digital converter when an input is below a first amplitude level, a second bit string from the second analog-to-digital converter when the input is above a second amplitude level, and a combination of the first bit string and the second bit string when the input is between the first and second amplitude levels.
- 22. A method of operating digital hearing aid, the method comprising:
receiving a bit string from a first analog-to-digital converter; receiving a bit string from a second analog-to-digital converter; and processing the first bit string from the first analog-to-digital converter when an input is below an amplitude level, and the second bit string from the second analog-to-digital converter when the input is above an amplitude level.
- 23. The method of claim 22 wherein the first analog-to-digital converter is a low-amplitude analog-to-digital converter, and the second analog-to-digital converter is a high-amplitude analog-to-digital converter.
- 24. The method of claim 23 wherein the amplitude level is a single amplitude level.
- 25. The method of claim 22, the method further comprising processing the first bit string from the first analog-to-digital converter when the input is below a first amplitude level, processing the second bit string from the second analog-to-digital converter when the input is above a second amplitude level, and processing a combination of the first and the second bit strings when the input is between the first and second amplitude levels.
- 26. The method of claim 22, the method further comprising triggering the sample conversion of both the first analog-to-digital converter and the second analog-to-digital converters from a single clock.
RELATED APPLICATIONS
[0001] The applicants claim priority based on provisional application Ser. No. 60/332,817, “Improved Dynamic Range Analog to Digital Converter Suitable for Hearing Aid Applications”, filed Nov. 15, 2001, the complete subject matter of which is incorporated herein by reference in its entirety.
Provisional Applications (1)
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Number |
Date |
Country |
|
60332817 |
Nov 2001 |
US |