WO2001050814A1 - Ensemble microphone avec separateur a transistor a effet de champ a jonctions (jfet) a puce a protuberance pour appareil de correction auditive - Google Patents

Ensemble microphone avec separateur a transistor a effet de champ a jonctions (jfet) a puce a protuberance pour appareil de correction auditive Download PDF

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Publication number
WO2001050814A1
WO2001050814A1 PCT/US2000/000252 US0000252W WO0150814A1 WO 2001050814 A1 WO2001050814 A1 WO 2001050814A1 US 0000252 W US0000252 W US 0000252W WO 0150814 A1 WO0150814 A1 WO 0150814A1
Authority
WO
WIPO (PCT)
Prior art keywords
hearing aid
backplate
pcb
jfet
terminal
Prior art date
Application number
PCT/US2000/000252
Other languages
English (en)
Other versions
WO2001050814A8 (fr
Inventor
Peter Madaffari
Walter P. Sjursen
Christopher Poux
Richard Moroney
Ponnusamy Palanisamy
Original Assignee
Sarnoff Corporation
Tibbetts Industries, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sarnoff Corporation, Tibbetts Industries, Inc. filed Critical Sarnoff Corporation
Priority to PCT/US2000/000252 priority Critical patent/WO2001050814A1/fr
Publication of WO2001050814A1 publication Critical patent/WO2001050814A1/fr
Publication of WO2001050814A8 publication Critical patent/WO2001050814A8/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/01—Electrostatic transducers characterised by the use of electrets
    • H04R19/016—Electrostatic transducers characterised by the use of electrets for microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
    • H04R25/60—Mounting or interconnection of hearing aid parts, e.g. inside tips, housings or to ossicles
    • H04R25/604—Mounting or interconnection of hearing aid parts, e.g. inside tips, housings or to ossicles of acoustic or vibrational transducers

Definitions

  • the performance of a hearing aid depends, among other things, upon the design of the microphone assembly which includes the microphone transducer, sound port, and a housing containing the signal processing electronics.
  • the microphone transducer is typically a variable capacitor or electret type microphone formed of a charged diaphragm forming one plate of the capacitor and a backplate forming the other terminal. Sound impinging on the diaphragm varies the capacitance and produces a voltage signal proportional to the sound waves which is picked off the backplate and coupled to signal processing circuits where it is amplified in an amplifier and electrically processed to, inter alia, reduce noise content. The processed signal is then coupled to a receiver and converted back to sound waves to aid the user.
  • hearing aids Conventional in the ear (ITE) or in the canal (ITC), hearing aids must of necessity be of relatively small size. Therefore, such aids have been fabricated with accessible replaceable batteries which are accessed via a faceplate door on the hearing aid enclosure. These size and battery requirements cause the microphone assembly and also the diaphragm to be relatively small in size in relation to the size of the hearing aid faceplate. The small diaphragm size lowers the quality of the transducer function.
  • An electret microphone for hearing aids typically uses a Junction Field Effect Transistor (JFET) buffer to convert the voltage signal from the high impedance transducer source to a low impedance source.
  • JFET Junction Field Effect Transistor
  • This impedance conversion typically requires a difficult connection to be made to a high quality and hence, expensive substrate on a Printed Circuit Board (PCB) containing the signal processing components, so as to avoid compromising the input impedance of an amplifier on the substrate.
  • PCB Printed Circuit Board
  • This invention is directed to a microphone assembly for a hearing aid comprising a metal housing with a front wall with sound openings and a side wall extending longitudinally away from the front wall.
  • an electret type microphone or transducer having a diaphragm electrode and a backplate electrode. External sound entering through the openings are converted into an electrical voltage signal which is coupled from the backplate to a Junction Field Effect Transistor (JFET) buffer device. The buffered signal is then coupled to an amplifier and signal processing components within the housing.
  • JFET Junction Field Effect Transistor
  • the JFET device is a flip-chip component with four active terminals. Drain, source, bias and gate terminals are provided. The gate terminal is located on a side of the flip-chip proximal to and adjacent the backplate. The other terminals are connected to respective traces on a PCB. All the signal processing circuits needed to provide a functional hearing aid are contained on the PCB.
  • the PCB also provides an acoustic seal to a back volume of the microphone and contains an electromagnetic interference (EMI) ground shield in the form of a ground plane of conductive material extending across the side wall of the housing.
  • EMI electromagnetic interference
  • Fig. 1 is a schematic side view of a first embodiment of the invention in which a microphone assembly contains a JFET buffer with source/drain flip-chip pads and a backside gate fastened to a microphone backplate.
  • Fig. 2 is an exploded view of the assembly of Fig. 1.
  • Fig. 3. is an enlarged schematic detail of the JFET buffer portion of Fig. 2 prior to assembly.
  • Fig. 4 is a detail as in Fig. 3 after assembly.
  • an electret microphone for hearing aids uses a JFET buffer to convert the signal from the backplate, i.e., a high impedance source (the microphone) to a low impedance source.
  • This impedance conversion results in a higher level loaded output signal level to the hearing aid amplifier than would be produced from the condenser microphone element itself without a buffer.
  • a JFET gate contact to the backplate of the microphone's condenser must somehow be made.
  • a direct connection from a small pad on the JFET to the microphone backplate is difficult to do and the use of an intermediate wire bond pad requires that the pad be mounted on ceramic, which complicates assembly.
  • the substrate must have high resistivity to not compromise the input impedance of the amplifier.
  • a ceramic (alumina) substrate has such properties.
  • the electrical connections for the JFET can be wire bonded from the microphone element onto a ceramic substrate.
  • wire bonds are normally formed with a loop from pads on the JFET to extra bonding pads on the ceramic substrate, a practice that requires extra space vertically and horizontally and produces stray capacitance to ground and other circuit nodes which reduce sensitivity and introduce noise.
  • Other disadvantages of a ceramic substrate itself are that it is relatively costly for use in a disposable hearing aid application. It also has a high dielectric constant which makes stray capacitance even higher.
  • the JFET backside gate 14 is connected to the backplate 12 by conductive epoxy 20. This keeps the connection to the JFET off the PCB substrate 18 so that a lower cost substrate such as a glass-epoxy printed circuit board (e.g., FR4) may be used. Since the JFET gate 14 does not contact the substrate 18 and then connect to the microphone backplate 12 (rather the JFET is connected to the backplate directly), the stray capacitance should be lower and, hence, sensitivity should be higher.
  • a glass-epoxy printed circuit board e.g., FR4
  • Fig. 1 is a sectional view of this embodiment of the hearing aid microphone module or assembly 100 and Fig. 2 is an exploded view of the assembly 100.
  • Assembly 100 contains all the electronic components other than the battery and a receiver necessary for a functional hearing aid.
  • a circular metallic cover 40 is provided with a large diameter opening 52 for passage of sound from a faceplate (not shown) of a hearing aid enclosure in which the assembly 100 is adapted to be disposed proximally adjacent thereto. Sound impinges on large circular diaphragm 54 supported and attached to circular frame 42 and underlying spacer 44 which prevents the diaphragm 54 from contacting backplate 12.
  • Backplate 12 in turn, is supported at its edges by an insulative bushing, such as, PTF and is disposed over PCB 16 and acoustically and electrically sealed to cover 40 by a conductive cement, such as, epoxy. This partial assembly is then attached by snap ring 48 to electrical component PCB 50.
  • Figs. 3 and 4 show details of the flip-chip JFET connections including the gate to backplate connection 14 using conductive epoxy 20.
  • Fig. 3 is an exploded view before assembly, while Fig. 4 shows the JFET after assembly with the PCB 16 and the backplate 12.
  • the metallization 22 on the top of the JFET die 10 is the gate connection, which is a very high impedance point.
  • a flip-chip JFET 10 with no gate contact made to the PCB allows use of low cost FR4 or other such materials instead of ceramic for the PCB substrate.
  • b. By controlling the depth of the front chamber 30 in the microphone assembly so that the spacing from the backplate to the PCB substrate is small enough, a single blob of conductive (epoxy) cement 20 is sufficient to bridge the gap, eliminating the need for wire bonds.
  • c. Stray capacitance from the gate to PCB substrate is reduced because of this gate isolation, resulting in decreased signal loss and decreased noise pickup.
  • the use of four dummy solder balls on JFET provides better mechanical support and alignment during assembly. (Solder bumps on Drain, Source, Bias, and NC solder bumps 752).

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Neurosurgery (AREA)
  • Otolaryngology (AREA)
  • Amplifiers (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)

Abstract

La présente invention concerne un module de microphone d'appareil de correction auditive qui intègre tous les composants électroniques nécessaires pour un appareil de correction auditive fonctionnel en dehors de l'accu et du récepteur, et qui utilise la technologie de la puce à protubérance pour coupler un séparateur JFET aux composants. Ce séparateur est placé sur une carte à circuit imprimé qui défini un volume de fond de cette enveloppe.
PCT/US2000/000252 2000-01-06 2000-01-06 Ensemble microphone avec separateur a transistor a effet de champ a jonctions (jfet) a puce a protuberance pour appareil de correction auditive WO2001050814A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2000/000252 WO2001050814A1 (fr) 2000-01-06 2000-01-06 Ensemble microphone avec separateur a transistor a effet de champ a jonctions (jfet) a puce a protuberance pour appareil de correction auditive

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2000/000252 WO2001050814A1 (fr) 2000-01-06 2000-01-06 Ensemble microphone avec separateur a transistor a effet de champ a jonctions (jfet) a puce a protuberance pour appareil de correction auditive

Publications (2)

Publication Number Publication Date
WO2001050814A1 true WO2001050814A1 (fr) 2001-07-12
WO2001050814A8 WO2001050814A8 (fr) 2001-12-27

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2000/000252 WO2001050814A1 (fr) 2000-01-06 2000-01-06 Ensemble microphone avec separateur a transistor a effet de champ a jonctions (jfet) a puce a protuberance pour appareil de correction auditive

Country Status (1)

Country Link
WO (1) WO2001050814A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004057909A2 (fr) * 2002-12-20 2004-07-08 Sonion Lyngby A/S Transducteur au silicium pouvant equiper des appareils de correction auditive et des appareils d'ecoute
EP1903834A1 (fr) * 2006-09-22 2008-03-26 Siemens Audiologische Technik GmbH Appareil auditif avec un capteur de champ magnétique et procédé de montage d'éléments éléctroniques sur un circuit

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4764690A (en) * 1986-06-18 1988-08-16 Lectret S.A. Electret transducing
US4922471A (en) * 1988-03-05 1990-05-01 Sennheiser Electronic Kg Capacitive sound transducer
EP0800331A2 (fr) * 1996-04-03 1997-10-08 Microtronic Nederland B.V. Unité de microphone/amplificateur intégrés, et un module d'amplificateur pour cette unité
US5684324A (en) * 1994-08-12 1997-11-04 The Charles Draper Laboratory, Inc. Acoustic transducer chip
US5856914A (en) * 1996-07-29 1999-01-05 National Semiconductor Corporation Micro-electronic assembly including a flip-chip mounted micro-device and method

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4764690A (en) * 1986-06-18 1988-08-16 Lectret S.A. Electret transducing
US4922471A (en) * 1988-03-05 1990-05-01 Sennheiser Electronic Kg Capacitive sound transducer
US5684324A (en) * 1994-08-12 1997-11-04 The Charles Draper Laboratory, Inc. Acoustic transducer chip
EP0800331A2 (fr) * 1996-04-03 1997-10-08 Microtronic Nederland B.V. Unité de microphone/amplificateur intégrés, et un module d'amplificateur pour cette unité
US5856914A (en) * 1996-07-29 1999-01-05 National Semiconductor Corporation Micro-electronic assembly including a flip-chip mounted micro-device and method

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004057909A2 (fr) * 2002-12-20 2004-07-08 Sonion Lyngby A/S Transducteur au silicium pouvant equiper des appareils de correction auditive et des appareils d'ecoute
WO2004057909A3 (fr) * 2002-12-20 2004-12-02 Sonion Lyngby As Transducteur au silicium pouvant equiper des appareils de correction auditive et des appareils d'ecoute
US7142682B2 (en) 2002-12-20 2006-11-28 Sonion Mems A/S Silicon-based transducer for use in hearing instruments and listening devices
US7792315B2 (en) 2002-12-20 2010-09-07 Epcos Ag Silicon-based transducer for use in hearing instruments and listening devices
EP1903834A1 (fr) * 2006-09-22 2008-03-26 Siemens Audiologische Technik GmbH Appareil auditif avec un capteur de champ magnétique et procédé de montage d'éléments éléctroniques sur un circuit

Also Published As

Publication number Publication date
WO2001050814A8 (fr) 2001-12-27

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