US 20020191802A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2002/0191802 A1
(43) Pub. Date:
Choc et al.
(54)
SYSTEMS AND METHODS FOR SENSING
AN ACOUSTIC SIGNAL USING
MICROELECTROMECHANICAL SYSTEMS
TECHNOLOGY
(52)
U.S. c1. ............................................ .. 381/92; 381/122
(57)
ABSTRACT
An acoustic system has an acoustic sensor and a processing
circuit. The acoustic sensor includes a base, a microphone
(76) Inventors: Howard C. Choe, Andover, MA (US);
Emel S. Bulat, Framingham, MA (US)
having a microphone diaphragm supported by the base, and
a hot-Wire anemometer having a set of hot-Wire extending
Correspondence Address:
David E. Huang, Esq.
members supported by the base. The set of hot-Wire extend
ing members de?nes a plane Which is substantially parallel
CHAPIN & HUANG, L.L.C.
Westborough O?ice Park
to the microphone diaphragm. The processing circuit
receives a sound and Wind pressure signal from the micro
1700 West Park Drive
phone and a Wind velocity signal from the hot-Wire
anemometer, and provides an output signal based on the
sound and Wind pressure signal from the microphone and the
Wind velocity signal from the hot-Wire anemometer (e.g.,
accurate sound With Wind noise removed). The con?guration
of the hot-Wire extending members de?ning a plane Which
is substantially parallel to the microphone diaphragm can be
easily implemented in a MEMS device making the con?gu
ration suitable for miniaturized applications.
Westborough, MA 01581 (US)
(21) Appl. No.:
09/881,793
(22) Filed:
Jun. 15, 2001
Publication Classi?cation
(51)
Dec. 19, 2002
Int. Cl.7 ..................................................... .. H04R 3/00
40
/
ADDITIONAL CIRCUITRY @
ACOUSTIC SENSOR Q
PROCESSING CIRCUIT ?
(E.G., MEMS DEVICE)
(E.G., ASIC)
(E.G.. RECORDER,
AMPLIFIER, ETC.)
/—I—._\
_,_,—__J____\
60
HOT-WIRE
-L>
ANEMOMETER @ I—>
(VELOCITY SENSING)
64
CONVERSION STAGE 2
(CONVERT/PREDICT
WIND PRESSURE)
I\ 62
MICROPHONE Q
l’
OUTPUT STAGE g (E.G.,
(SOUND AND WIND
I-———>
SUBTRACTION
PRESSURE SENSING)
M) CONVERTER @
OPERATION)
I\ 68
DIGITAL SIGNAL
PROCESSOR 58
T>
~
Patent Application Publication Dec. 19, 2002 Sheet 1 0f 22
US 2002/0191802 A1
40
/
ACOUSTIC SENSOR Q
PROCESSING CIRCUIT 4i
(EG, MEMS DEVICE)
(E.G., ASIC)
ADDITIONAL CIRCUITRY @
(E.G., RECORDER,
AMPLIFIER, ETC)
,_,._—I_
’—_J___\
60
HOT-WIRE
—L>
ANEIvIOIvIETER @
(VELOCITY SENSING)
CONVERSION STAGE 2
>
64
(CONVERT/PREDICT
WIND PRESSURE)
b 62
MICROPHONE §_0_
_L>
OUTPUT STAGE g (E.G,,
(SOUND AND WIND
‘-—————>
SUBTRACTION
PRESSURE SENSING)
A/D CONVERTER 5—6
OPERATION)
FIG. 1
b as
DIGITAL SIGNAL
T}
PROCESSOR 5_81
Patent Application Publication Dec. 19, 2002 Sheet 2 0f 22
US 2002/0191802 A1
70
84
78-A
78-B
FIG. 2
Patent Application Publication Dec. 19, 2002 Sheet 3 0f 22
US 2002/0191802 A1
Patent Application Publication Dec. 19, 2002 Sheet 4 0f 22
US 2002/0191802 A1
110
42
FIG. 4
Patent Application Publication Dec. 19, 2002 Sheet 5 0f 22
US 2002/0191802 A1
120
124-A
\\
122-A
\
\
78-A f
78-B /
78-C /
78-D /
J
(
122-A
124-5 \
FIG. 5
78-E /
78-F /
Patent Application Publication Dec. 19, 2002 Sheet 6 0f 22
US 2002/0191802 A1
130
PROVIDE A MICROPHONE AND A HOT-WIRE ANEMOMETER, THE
HOT-WIRE ANEMOMETER HAVING A SET OF HOT-WIRE EXTENDING
MEMBERS THAT DEFINES A PLANE WHICH IS SUBSTANTIALLY PARALLEL
TO A MICROPHONE DIAPHRAGM OF THE MICROPHONE (E.G., PROVIDE A
MEMS DEVICE INCLUDING AN ACOUSTIC SENSOR HAVING A
MICROPHONE ELEMENT AND A CO-LOCATED HOT-WIRE ANEMOMETER
ELEMENT, PROVIDE A MEMS DEVICE INCLUDING AN ARRAY OF
MICROPHONE AND HOT-WIRE ELEMENTS, ETC.)
\
I32
I
GENERATE A SOUND AND WIND PRESSURE SIGNAL IN RESPONSE TO
SOUND AND WIND PRESSURE ON THE MICROPHONE DIAPHRAGM (E.G.,
SENSE SOUND AND WIND PRESSURE USING THE MEMS DEVICE)
GENERATE A WIND VELOCITY SIGNAL IN RESPONSE TO WIND VELOCITY
ON THE SET OF HOT-WIRE EXTENDING MEMBERS OF THE HOT-WIRE
ANEMOMETER (E.G.‘ SENSE WIND VELOCITY USING THE MEMS DEVICE)
l
PROVIDE AN OUTPUT SIGNAL BASED ON THE GENERATED SOUND AND
WIND SIGNAL AND THE GENERATED WIND VELOCITY SIGNAL (E.G.,
CONVERT THE WIND VELOCITY SIGNAL INTO AN ANALOG WIND
PRESSURE SIGNAL HAVING A WIND PRESSURE COMPONENT AND
SUBSTRACT THE WIND PRESSURE COMPONENT OF THE ANALOG WIND
PRESSURE SIGNAL FROM THE SOUND AND WIND PRESSURE SIGNAL;
DIGITIZE THE WIND VELOCITY SIGNAL‘ CORRELATE WITH A SERIES OF
WIND PRESSURE VALUES FROM A LOOKUP TABLE, AND SUBTRACT THE
SERIES OF WIND PRESSURE VALUES FROM THE SOUND AND WIND
PRESSURE SIGNAL; ETC.)
\136
Patent Application Publication Dec. 19, 2002 Sheet 7 0f 22
US 2002/0191802 A1
140
OPTIONALLY
TUNED TO
A FIRST
FREQUENCY
RANGE
OPTIONALLY
TUNED TO
A SECOND
FREQUENCY
RANGE
OPTIONALLY
TUNED TO
A THIRD
FREQUENCY
RANGE
(E.G., O-1OKHZ)
(E.G., “IO-ZOKHZ)
(E.G., 20-3OKHZ)
Patent Application Publication Dec. 19, 2002 Sheet 8 0f 22
US 2002/0191802 A1
150
L00 KUP TABLE(S) @
(WIND PRESSURE
VALUES)
$160
CORRELATION STAGE ?>§
(DIGITIZE AND APPLY
ALGORITHM TO
CORRELATE TO SERIES
OF WIND PRESSURE
VALUES)
60)
HOT-WIRE
CONVERSION STAGE 5_2
ANEMOMETER 4g
(CONVERT/PREDICT WIND
(VELOCITY SENSING)
PRESSURE)
£162
ADDITIONAL
MICROPHONE Q
(SOUND AND WIND
——>
OUTPUT STAGE 1g (E.G.,
SUBTRACTION
PRESSURE SENSING)
Tb
OPERATION)
64
;|—___’
ACOUSTIC SENSOR 4_2
\_—l—_—/
PROCESSING CIRCUIT 35g
(EG, MEMS DEvICE)
(E.G., ASIC)
FIG. 8
CIRCUITRYE
(E.G., RECORDER,
AMPLIFIER,
TRANSMITTER, ETC.)
Patent Application Publication Dec. 19, 2002 Sheet 9 0f 22
US 2002/0191802 A1
200
208-A
1
'
208-8
l
l
208-0
'
l
'
I
K 208
‘ \ 206
4
204
\ 202
FIG. 9
210
206-A
1
'
206-5
|
I
'
K
I
206-0
l
l
K 206
_
204
\ 202
FIG. 10
220
224-A
224-5
224-c
224-0 324
222
204
202
FIG. 11
Patent Application Publication Dec. 19, 2002 Sheet 10 0f 22
US 2002/0191802 A1
230
222~A
I
(
206-A
222-B
J
I
222-C
J
1
206-8
222-D
206-C
\ 204
\ 202
FIG. 12
240
222-A
I}
242-A
I
222-5
206-A
(I
242-5
I)
K
2220 242-0
I}
206-8
(I
222-D
206-0
I
‘ ~ 204
\ 202
FIG. 13
250
222-A
242-A
206-A
222-B
242-5
“
2220 242-0
252 222-D
206-5
204
202
FIG. 14
Patent Application Publication Dec. 19, 2002 Sheet 11 0f 22
US 2002/0191802 A1
260
K
206
262
r \4
252
204
202
FIG. 15
270
206
i
272
f
252
222
204
202
FIG. 16
280
206
g
272
282
...._CI.EIEIEIEI.EI__
252
204
202
FIG. 17
Patent Application Publication Dec. 19, 2002 Sheet 12 0f 22
US 2002/0191802 A1
290
292-A
292-8
Q2
“
292-0
292
Q2
1
‘
DECIDED
w
\ 282
DDEIEIUEI
DDCIEIEID
“\252
r—"—|
|*—1
206
|—"—|
-
204
\ 202
FIG. 18
300
272
DDDDDCI
DEIEIEIEID
252
204
202
FIG. 19
Patent Application Publication Dec. 19, 2002 Sheet 13 0f 22
US 2002/0191802 A1
310
i
272
314
{- \4
312
252
204
202
FIG. 20
320
$
322
312
252
204
202
FIG. 21
Patent Application Publication Dec. 19, 2002 Sheet 14 0f 22
US 2002/0191802 A1
330
272
322
‘L
332
312
DDUDDEI
242
252
206
204
202
FIG. 22
340
322
272
332
312
252
204
202
342-A
“
342-5
342-c
FIG. 23
342-0
342
Patent Application Publication Dec. 19, 2002 Sheet 15 0f 22
US 2002/0191802 A1
350
272
$
332
312
252
204
202
342-A
342-5
342-0
342-0
342
FIG. 24
360
322
272
332
3'12
DDIJDDD
2g
252
206
204
202
352-C
352-B
FIG. 25
352-A
Patent Application Publication Dec. 19, 2002 Sheet 16 0f 22
US 2002/0191802 A1
400
410-A
410-5
410-0
$
410
1
406
404
402
408
FIG. 26
420
406-A
406-B
rafa
406-C
i
rah
406
J
ii
\ 404
FIG. 27
430
406
432
404
402
408
FIG. 28
Patent Application Publication Dec. 19, 2002 Sheet 17 0f 22
US 2002/0191802 A1
440
442-A 406
IL
442-B
*
Il
442-0
[1|
_\ 404
'\ 402
“‘~ 408
FIG. 29
450
456-0
456-5
456-A
454
408
402
404
452
406
FIG. 30
Patent Application Publication Dec. 19, 2002 Sheet 18 0f 22
US 2002/0191802 A1
460
322
i
x
BUD
272
DD
DEIUCIUD
DECIDED
\ 312
UUUUDD
206
DDUUEIEI
UDUCIDU
"
‘
352-0
352-5
352-A
456-0
456-B
456~A
|I
||
|I
204
_\ 202
\ 408
\ 402
%_| |__]
406 T
442.9
L___| |_|
|__| L._|
T
T
4425
442-A
FIG. 31
_
404
Patent Application Publication Dec. 19, 2002 Sheet 19 0f 22
US 2002/0191802 A1
470
FORM A MICROPHONE DIAPHRAGM OVER A SUBSTRATE OF A BASE
STRUCTURE
\
472
DISPOSE A FIRST LAYER OF MATERIAL OVER THE BASE STRUCTURE
47
DISPOSE A SECOND LAYER OF MATERIAL OvER THE FIRST LAYER OF
MATERIAL (E.G., POSITION TUNGSTEN OvER THE FIRST LAYER OF
MATERIAL USING A CHEMICAL VAPOR DEPOSITION PROCESS, RAPID
THERMAL PROCESSING, ETC)
\
476
REMOVE AT LEAST A PORTION OF THE FIRST LAYER OF MATERIAL AND A
PORTION OF THE SECOND LAYER OF MATERIAL SUCH THAT A
REMAINDER OF THE SECOND LAYER OF MATERIAL FORMS MULTIPLE
EXTENDING MEMBERS SUPPORTED BY THE BASE STRUCTURE, THE
EXTENDING MEMBERS BEING PARALLEL TO EACH OTHER (E.G., SUCH
THAT THE MICROPHONE DIAPHRAGM RESIDES BETWEEN THE
EXTENDING MEMBERS AND THE SUBSTRATE, AND SUCH THAT THE
_ TEMPERATURE
EXTENDING MEMBERS ARE CAPABLE OF OPERATING AS A PORTION OF A
HOT-WIRE ANEMOMETER)
\
I
478
REMOVE A PORTION OF THE SUBSTRATE (E.G., VIA ANISOTROPIC
ETCHING) TO FORM A FIRST PORTION OF A CONDENSER MICROPHONE
CAVITY
\
48 O
FORM A RIGID MEMBER OVER ANOTHER SUBSTRATE, REMOVE A
PORTION OF THE OTHER SUBSTRATE (E.G., VIA ANISOTROPIC ETCHING)
TO FORM A SECOND PORTION OF THE CONDENSER MICROPHONE
CAVITYI AND BOND THE SUBSTRATE WITH THE OTHER SUBSTRATE (E.G.,
VIA ANODIC BONDING) SUCH THAT THE FIRST AND SECOND PORTIONS OF
THE CONDENSER MICROPHONE CAVITY ALIGN AND SUCH THAT THE
MICROPHONE DIAPHRAGM IS DISPOSED BETWEEN THE EXTENDING
MEMBERS AND TEH CONDENSER MICROPHONE CAVITY TO FORM, AS A
MEMS DEVICE, AN ACOUSTIC ELEMENT HAVING A HOT-WIRE
ANEMOMETER AND A CO-LOCATED CONDENSER MICROPHONE
FIG. 32
MEMS
STEPS
MAINTAINING
A
RANGE THAT
Is LESS
THAN 700
DEGRESS
CELSIUS