Amplification Circuit and Hearing Aid

• US 20100061576A1
• Filed: 09/09/2008
• Published: 03/11/2010
• Est. Priority Date: 09/09/2008
• Status: Active Grant

• Current Assignee: Etymotic Research Incorporated
• Original Assignee: Etymotic Research Incorporated
• Inventors: Johnson, William A., Killion, Mead C.
• Granted Patent: US 8,160,284 B2
• Time in Patent Office: Days
• US Class Current: 381/322
• CPC Class Codes: H03F 1/307 in push-pull amplifiers
• CPC Class Codes: H03F 2200/03 the amplifier being designed for audio applications
• CPC Class Codes: H03F 3/26 Push-pull amplifiers; Phase-splitters therefor duplicated single-ended push-pull arrangements or phase-splitters therefor H03F3/30
• CPC Class Codes: H03F 3/3066 the collectors of complementary power transistors being connected to the output
• CPC Class Codes: H04R 2225/33 Aspects relating to adaptation of the battery voltage, e.g. its regulation, increase or decrease
• CPC Class Codes: H04R 2460/17 Hearing device specific tools used for storing or handling hearing devices or parts thereof, e.g. placement in the ear, replacement of cerumen barriers, repair, cleaning hearing devices
• CPC Class Codes: H04R 25/48 using constructional means for obtaining a desired frequency response H04R25/652 takes precedence
• CPC Class Codes: H04R 25/654 Ear wax retarders
• CPC Class Codes: H04R 25/656 Non-customized, universal ear tips, i.e. ear tips which are not specifically adapted to the size or shape of the ear or ear canal

Abstract

Certain embodiments of the present technology provide improved amplification circuits and hearing aids that can utilize such amplification circuits. In an embodiment, for example, an amplification circuit includes: a first sub circuit configured to create a voltage drop when a supply voltage is above a first voltage; and a second sub circuit configured to create a reverse voltage drop when the supply voltage is below a second voltage, wherein the first and second sub circuits operate to maintain idling current within a range. Certain embodiments of the present technology also provide hearing aids that include removable dampers.

Claims

1. An amplification circuit comprising:

a first sub circuit configured to create a voltage drop when a supply voltage is above a first voltage; and

a second sub circuit configured to create a reverse voltage drop when the supply voltage is below a second voltage,

wherein the first and second sub circuits operate to maintain idling current within a range.

2. The amplification circuit of claim 1, wherein the voltage drop is across a plurality of resistors such that a base emitter voltage of a plurality of transistors is independent of supply voltage above the first voltage.

3. The amplification circuit of claim 1, wherein the reverse voltage drop is across a plurality of resistors such that a base emitter voltage of a plurality of transistors is independent of supply voltage below the second voltage.

4. The amplification circuit of claim 1, wherein the second sub circuit is disabled when the supply voltage is above a third voltage.

5. The amplification circuit of claim 4, wherein the first voltage is about volts, the second voltage is about 1 volt, and the third voltage is about 1.2 volts.

6. The amplification circuit of claim 1, wherein the first sub circuit and the second sub circuit are provided on the same die and have the same temperature coefficient.

7. The amplification circuit of claim 1, further comprising:

a first output and a second output, wherein the outputs are configured to be used with a two-terminal receiver.

8. The amplification circuit of claim 7, wherein the second output is configured to provide an output that is 180 degrees out of phase with the output provided by the first output.

9. The amplification circuit of claim 8, wherein the circuit provides an output without the use of output capacitors.

10. The amplification circuit of claim 1, wherein the circuit is configured to be used in a hearing aid.

11. A method for maintaining idling current of an amplification circuit within a range, the method comprising:

creating a voltage drop when a supply voltage is above a first voltage; and

creating a reverse voltage drop when the supply voltage is below a second voltage.

12. The method of claim 11, wherein the voltage drop is across a plurality of resistors such that a base emitter voltage of a plurality of transistors is independent of supply voltage above the first voltage, and wherein the reverse voltage drop is across a plurality of resistors such that a base emitter voltage of a plurality of transistors is independent of supply voltage below the second voltage.

13. A hearing aid comprising:

a housing;

a microphone configured to convert ambient sound into electrical signals;

an amplification circuit configured to process electrical signals received from the microphone;

a receiver configured to convert processed signals received from the amplification circuit into sound; and

a removable damper configured to smooth the frequency response of sound provided by the receiver.

14. The hearing aid of claim 13, wherein the damper is mounted with the housing.

15. The hearing aid of claim 13, further comprising an eartip configured to be removably attached to the housing, wherein the damper is mounted with the eartip.

16. The hearing aid of claim 13, wherein the damper includes a filter configured to block debris.

17. The hearing aid of claim 13, wherein frequency response accuracy is at least 80 percent.

18. The hearing aid of claim 13, further including a battery, wherein the battery drain is less than 0.5 mA.

19. The hearing aid of claim 13, farther comprising a switch operably connected to the amplification circuit, wherein the switch is configured to provide gain at a first setting and a second setting.

20. The hearing aid of claim 19, wherein the first setting can provide at least about 15 dB of gain for quieter sounds and about 0 dB of gain for louder sounds, wherein the second setting can provide at least about 23 dB of gain for quieter sounds and about 8 dB of gain for louder sounds, and wherein quieter sounds are sounds below about 50-60 dB and louder sounds are sounds above about 85-90 dB.

21. The hearing aid of claim 13, further comprising a volume controller operably connected to the amplification circuit, wherein the volume controller is configured to provide for increasing and decreasing gain.

22. The hearing aid of claim 21, wherein the volume controller is configured to provide a range of gain for quieter sounds from about 5 dB to about 23 dB and a corresponding range of gain for louder sounds from about −

10 dB to about 8 dB, and wherein quieter sounds are sounds below about 50-60 dB and louder sounds are sounds above about 85-90 dB.

23. The hearing aid of claim 13, wherein the amplification circuit includes:

a first sub circuit configured to create a voltage drop when a supply voltage is above a first voltage; and

a second sub circuit configured to create a reverse voltage drop when the supply voltage is below a second voltage,

wherein the first and second sub circuits operate to maintain idling current within a range.