US5559892A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impedence buffering MOS circuit with dynamically reduced threshold voltage, as for use in an output buffer of a hearing aid amplifier
Assignee: Knowles Electronics LLC
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Filing: 1994-03-28
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Granted: 1996-09-24
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Expires: 2014-03-28
Abstract
Abstract A buffer circuit, such as for use with a low voltage hearing aid, is disclosed. The hearing aid comprises a microphone, a receiver and an amplifier. The amplifier is disposed between the microphone and the receiver. The buffer circuit has a MOS device including a well terminal and a gate terminal equipotentially coupled together to reduce the effective threshold voltage of the MOS device, thereby reducing the gate-to-source voltage of the MOS device. This permits a greater linear output signal range for the amplifier.
Inventors
- 👤 Steven E. Boor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:04
CPC Classifications
H; H04; H04R; H04R25/00; H04R25/50; H04R25/502; G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/24
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
149 words
An impedence buffering circuit for permitting smooth signal flow from a first transmission medium to a second transmission medium comprising: an input adapted for coupling to the first transmission medium for receiving a signal; a MOS transistor coupled through the input to the first transmission medium for transforming the impedance imposed on the signal, the MOS transistor including a well terminal and a gate terminal both having an AC potential that is substantially equal to the input AC potential, such that the threshold voltage V T of the MOS transistor is reduced to reduce the gate-to-source voltage of the MOS transistor; and means for reducing the threshold voltage V T of the MOS transistor to reduce the gate-to-source voltage of the MOS transistor; an output coupled to the MOS transistor and adapted for coupling to the second transmission medium for conveying the impedence-transformed signal to the second transmission medium.
Claim 2
Dependent Claim
149 words
An impedence buffering circuit for permitting smooth signal flow from a first transmission medium to a second transmission medium comprising: an input adapted for coupling to the first transmission medium for receiving a signal; a MOS transistor coupled through the input to the first transmission medium for transforming the impedance imposed on the signal, the MOS transistor including a well terminal and a gate terminal both having an AC potential that is substantially equal to the input AC potential, such that the threshold voltage V T of the MOS transistor is reduced to reduce the gate-to-source voltage of the MOS transistor; and means for reducing the threshold voltage V T of the MOS transistor to reduce the gate-to-source voltage of the MOS transistor; an output coupled to the MOS transistor and adapted for coupling to the second transmission medium for conveying the impedence-transformed signal to the second transmission medium.
Claim 3
Dependent Claim
31 words
The impedence buffering circuit of claim 1, wherein the first transmission medium is coupled to a hearing aid microphone, and the second transmission medium is coupled to a hearing aid receiver.
Claim 4
Independent Claim
150 words
A device for converting sound to a corresponding amplified signal, the device comprising: an electret microphone including a charged plate and an FET, the FET having an input and an output, said charged plate being coupled to said input of said FET; an amplifier having an input and an output, said amplifier input being coupled to said output of said FET, said amplifier output having an output impedance; buffer means coupled to said output of said amplifier, said buffer means having a buffer input impedance substantially equal to the output impedance of said amplifier and a buffer output impedance substantially less than said amplifier output impedance, said buffer means including a MOS device having a well terminal and a gate terminal both equipotentially coupled to the buffer input, such that the threshold voltage V T of the MOS device is reduced to reduce the gate-to-source voltage of the MOS device.
Claim 5
Independent Claim
150 words
A device for converting sound to a corresponding amplified signal, the device comprising: an electret microphone including a charged plate and an FET, the FET having an input and an output, said charged plate being coupled to said input of said FET; an amplifier having an input and an output, said amplifier input being coupled to said output of said FET, said amplifier output having an output impedance; buffer means coupled to said output of said amplifier, said buffer means having a buffer input impedance substantially equal to the output impedance of said amplifier and a buffer output impedance substantially less than said amplifier output impedance, said buffer means including a MOS device having a well terminal and a gate terminal both equipotentially coupled to the buffer input, such that the threshold voltage V T of the MOS device is reduced to reduce the gate-to-source voltage of the MOS device.
Claim 6
Independent Claim
163 words
A device for converting sound to a corresponding amplified signal, the device comprising: a low voltage power supply; an electret microphone including a charged plate and an FET, the FET having an input and an output, said charged plate being coupled to said input of said FET; an amplifier having an input and an output, said amplifier input being coupled to said output of said FET, said amplifier output having an output impedance; and, buffer means coupled to said output of said amplifier, said buffer means having a buffer input impedance substantially equal to the output impedance of said amplifier and a buffer output impedance substantially less than said amplifier output impedance, said buffer means including a MOS device having a well terminal and a gate terminal both having an AC potential that is substantially equal to the input AC potential, such that the threshold voltage V T of the MOS device is reduced to reduce the gate-to-source voltage of the MOS device.
Claim 7
Independent Claim
163 words
A device for converting sound to a corresponding amplified signal, the device comprising: a low voltage power supply; an electret microphone including a charged plate and an FET, the FET having an input and an output, said charged plate being coupled to said input of said FET; an amplifier having an input and an output, said amplifier input being coupled to said output of said FET, said amplifier output having an output impedance; and, buffer means coupled to said output of said amplifier, said buffer means having a buffer input impedance substantially equal to the output impedance of said amplifier and a buffer output impedance substantially less than said amplifier output impedance, said buffer means including a MOS device having a well terminal and a gate terminal both having an AC potential that is substantially equal to the input AC potential, such that the threshold voltage V T of the MOS device is reduced to reduce the gate-to-source voltage of the MOS device.
Claim 8
Dependent Claim
22 words
The device of claim 4 wherein said low voltage power supply comprises a battery having a voltage of 1.5 v or less.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-09-24 | 2000-03-25 | 2000-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-09-24 | 2004-03-25 | 2004-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-09-24 | 2008-03-25 | 2008-09-24 | $7700.00 | Window Closed / Lapsed |