close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2001231098

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2001231098
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone device provided with an electret capacitor formed in a semiconductor substrate.
[0002]
2. Description of the Related Art A circuit diagram of a conventional microphone unit MU2 is
shown in FIG. The microphone arrangement MU2 comprises an electret condenser EC. When the
electret capacitor EC receives a sound pressure, its capacitance value changes, and an input
signal Vin is generated between its both electrodes. Therefore, the voice information is reflected
on the input signal Vin. Further, at both ends of the electret capacitor EC, an impedance
conversion circuit including diodes D1 and D2, a resistor R1 and N channel MOS type transistors
T1 and T2 is connected. Specifically, the anode of the diode D1 is connected to one electrode of
the electret capacitor EC, and the cathode is connected to the other electrode of the electret
capacitor EC. Further, with regard to the diode D2, the anode and the cathode are reversely
connected to the diode D1 and are connected to both ends of the electret capacitor EC.
Furthermore, a resistor R1 is connected in parallel across the electret capacitor EC. The source of
the transistor T1 is connected to the other electrode of the electret capacitor EC, and the gate is
connected to one electrode of the electret capacitor EC. The source of the transistor T2 is
connected to the drain of the transistor T1. The power supply potential Vdd is applied to the
drain of the transistor T2, and the constant potential Vref1 is applied to the gate. The ground
potential GND is applied to the back gates of the transistors T1 and T2. The ground potential
GND is also applied to the other electrode of the electret capacitor EC.
10-04-2019
1
[0003]
The voltage between the gate and the source of the transistor T1 is maintained at 0 [V] by the
diodes D1 and D2 and the resistor R1 when the input signal Vin is not given. The capacitance
value of the electret capacitor EC changes due to sound pressure, and when the input signal Vin
is generated, the voltage between the gate and the source of the transistor T1 fluctuates. Then,
the current flowing between the drain and the source changes accordingly. The transistor T1 is a
depletion type, and current flows between the drain and the source even if the voltage between
the gate and the source is 0 [V]. By the change of the drain-source current of the transistor T1,
the current flowing between the drain-source of the transistor T2 also changes, and the gatesource voltage of the transistor T2 fluctuates. The fluctuation of the potential at the source of the
transistor T2 is the output signal Vout. The phase of the output signal Vout is reverse to the
phase of the input signal Vin. When the value of the input signal Vin decreases, the value of the
output signal Vout increases, and when the value of the input signal Vin increases, the value of
the output signal Vout Decreases.
[0004]
Now, an example of a specific structure of the electret capacitor EC is shown in FIG. The electret
capacitor EC includes the wiring film IL2 formed on the semiconductor substrate SB as one
electrode. The wiring film IL2 is formed on the semiconductor substrate SB via the insulating
films IF1 and IF2. In addition, the electret capacitor EC is provided above the semiconductor
substrate SB with a space from the wiring film IL2 as the other electrode of the electret film EL
made of a dielectric in which a fixed amount of electrostatic charge is fixed semipermanently.
The electret film EL is a vibrating film that vibrates by receiving sound pressure. In FIG. 6, the
ground potential GND is applied to the electret film EL.
[0005]
The semiconductor substrate SB is, for example, a silicon substrate, and in FIG. 6, the
semiconductor substrate SB contains, for example, a P-type impurity. The ground potential GND
is applied to the semiconductor substrate SB. Then, over the insulating film IF1, a wiring film IL5
which is a wiring in the circuit is formed, and an insulating film IF2 is formed so as to cover the
insulating film IF1 and the wiring film IL5. The insulating films IF1 and IF2 are, for example, an
10-04-2019
2
oxide film or a nitride film, and the wiring films IL2 and IL5 are, for example, conductive films
made of Al or the like. Further, an insulating protective film PF is formed on the upper surfaces
of the wiring film IL2 and the insulating film IF2, and covers these films. The protective film PF is
also, for example, an oxide film or a nitride film.
[0006]
Further, although not shown in FIG. 6, diodes D1 and D2 and resistors R1 and transistors T1 and
T2 in FIG. 5 are also formed in the semiconductor substrate SB around the portion where the
electret capacitor EC is formed.
[0007]
The electret capacitor EC has a structure as shown in FIG. 6, and a wiring film IL2 which is one
electrode of the electret capacitor EC is formed on the surface of the semiconductor substrate SB.
A parasitic capacitance is generated between the and the wiring film IL2.
In FIG. 5, this parasitic capacitance is represented as CX. Since the ground potential GND is
applied to the semiconductor substrate SB which is one electrode of the parasitic capacitance CX,
one electrode of the parasitic capacitance CX is at the same potential as the electret film EL.
Therefore, the parasitic capacitance CX is in parallel with the electret capacitor EC.
[0008]
In addition, parasitic capacitance is also generated between the gate and the source of the
transistor T1. In FIG. 5, this parasitic capacitance is represented as CG.
[0009]
Now, let Ce be the capacitance value of the electret capacitor EC, and Q be the charge amount of
a fixed amount of electrostatic charge held by the electret film EL, then the gate of the transistor
T1 when the above parasitic capacitances CX and CG do not exist. The voltage between sources,
that is, the input signal Vin is Vin = Q / Ce. Therefore, assuming that Ce = 1.0 [pF], the input
signal Vin becomes Q / (1.0 × 10 −12) [V].
10-04-2019
3
[0010]
However, considering the existence of the parasitic capacitances CX and CG, and considering the
voltage Vin between the gate and the source, the value is Vin = Q / (Ce + Cx + Cg). Here, Cx
represents the capacitance value of the parasitic capacitance CX, and Cg represents the
capacitance value of the parasitic capacitance CG. Assuming that the capacitance Ce is the same
as above and the sum of the capacitances Cx and Cg is Cx + Cg = 9.0 [pF], the input signal Vin is
Q / (10.0 × 10 −12) [V]. Thus, when the parasitic capacitances CX and CG exist, the value of the
input signal Vin becomes 1/10 compared to the case where the parasitic capacitances CX and CG
do not exist, and the signal input between the gate and source of the transistor T1 becomes
weak. It will
[0011]
That is, when the parasitic capacitances CX and CG exist, the value of the input signal Vin
decreases and a change hardly occurs, so that the sensitivity as the microphone device is
lowered.
[0012]
Therefore, the present invention is to realize a microphone device capable of suppressing a
decrease in sensitivity due to parasitic capacitance generated with the structure of an electret
capacitor.
[0013]
The invention according to claim 1 is characterized in that an electret capacitor having one
electrode and the other electrode and a voltage generated between the one electrode and the
other electrode of the electret capacitor are amplified for output. A microphone device
comprising: an amplifier; and a capacitor having one electrode to which the output of the
amplifier is given and the other electrode connected to the one electrode of the electret capacitor.
[0014]
According to a second aspect of the present invention, a semiconductor substrate to which a
fixed potential is applied, an insulating layer formed on the semiconductor substrate, a one
electrode formed on the insulating layer, and the fixed potential are applied. An electret capacitor
10-04-2019
4
having a vibrating other electrode separated from the one electrode by a space, an amplifier for
amplifying and outputting a voltage generated between the one electrode and the other electrode
of the electret capacitor, and the electret capacitor And a conductive layer which is formed under
the insulating layer to be opposed to the one electrode of the conductive layer and to which the
output of the amplifier is given.
[0015]
The invention according to claim 3 is the microphone device according to claim 2, wherein the
conductive layer is an impurity layer formed on the surface of the semiconductor substrate under
the insulating layer.
[0016]
The invention according to claim 4 is the microphone device according to claim 3, further
comprising a wiring layer formed on the insulating layer, connected to the conductive layer
through the insulating layer. It is.
[0017]
The invention according to claim 5 is the microphone device according to claim 2, wherein the
insulating layer is formed on a first insulating film formed on the semiconductor substrate and a
second insulating film formed on the first insulating film. The microphone device may have an
insulating film, and the conductive layer may be a wiring layer formed on the first insulating film
and the second insulating film.
[0018]
DESCRIPTION OF THE PREFERRED EMBODIMENTS First Preferred Embodiment FIG. 1 shows a
microphone device MU1 according to a preferred embodiment of the present invention.
The microphone device MU1 is also provided with an electret condenser EC, like the microphone
device MU2 shown in FIG.
When the electret capacitor EC receives a sound pressure, the capacitance value changes, and an
input signal Vin is generated between the both electrodes.
10-04-2019
5
The anode of the diode D1 is connected to one electrode of the electret capacitor EC, and the
cathode is connected to the other electrode of the electret capacitor EC.
As for the diode D2, the anode and the cathode are reversely connected to the diode D1 and
connected in parallel to both ends of the electret capacitor EC.
Furthermore, a resistor R1 is connected in parallel across the electret capacitor EC.
The source of the transistor T1 is connected to the other electrode of the electret capacitor EC,
and the gate is connected to one electrode of the electret capacitor EC.
The source of the transistor T2 is connected to the drain of the transistor T1. The power supply
potential Vdd is applied to the drain of the transistor T2, and the constant potential Vref1 is
applied to the gate. The ground potential GND is applied to the back gates of the transistors T1
and T2. The ground potential GND is also applied to the other electrode of the electret capacitor
EC. A parasitic capacitance CG is shown between the gate and the source of the transistor T1. The
parasitic capacitance CX will be described later.
[0019]
The operation of the impedance conversion circuit including the electret capacitor EC and the
diodes D1 and D2, the resistor R1 and the transistors T1 and T2 is the same as that of the
microphone device MU2, and thus the description thereof is omitted.
[0020]
Now, the microphone device MU1 according to the embodiment of the present invention further
includes operational amplifiers OP1 and OP2 and resistors R2 and R3.
The output signal Vout at the drain of the transistor T1 is also input to the positive input terminal
of the operational amplifier OP1 in addition to being output as a signal. The output signal of the
operational amplifier OP1 is input to the negative input terminal of the operational amplifier
OP1, and the operational amplifier OP1 functions as a voltage follower. The voltage follower is
10-04-2019
6
provided to extract a voltage signal without affecting the circuit on the input side. Therefore, as
long as the output signal Vout can be detected without affecting the current flowing between the
drain and source of the transistors T1 and T2, the operational amplifier OP1 may be omitted.
[0021]
The output signal of the operational amplifier OP1 is input to the negative input terminal of the
operational amplifier OP2 via the resistor R2. The output signal Vfb of the operational amplifier
OP2 is also input to the negative input terminal of the operational amplifier OP2 via the resistor
R3, and the operational amplifier OP2 functions as an inverting amplifier. The constant potential
Vref2 is applied to the positive input terminal of the operational amplifier OP2.
[0022]
The inverting amplifier is provided to feed back the output signal Vout to one electrode of the
electret capacitor EC. The output signal Vfb of the operational amplifier OP2 is a feedback signal
in phase with the input signal Vin, which is generated by inverting and amplifying the output
signal Vout. The output signal Vfb is in phase with the input signal Vin because the phase of the
output signal Vout is inverted with the phase of the input signal Vin and is further inverted by
the operational amplifier OP2. The amplification factor of the output signal Vfb with respect to
the input signal Vin is a product of the amplification factor of the output signal Vout of the
transistor T1 with respect to the input signal Vin and the amplification factor of the output signal
Vfb of the operational amplifier OP2. Therefore, it is also considered that this inverting amplifier
constitutes an amplifier together with the transistor T1.
[0023]
As for the parasitic capacitance CX, one electrode in FIG. 5 is the semiconductor substrate SB,
and the ground potential GND is given to the semiconductor substrate SB. Therefore, the
expression of parallel connection to the electret capacitor EC is made. However, in the present
embodiment, in order to feed back the output signal Vfb to one electrode of the electret capacitor
EC, not the ground potential GND but the output signal Vfb is applied to one electrode of the
parasitic capacitance CX. Therefore, in FIG. 1, the parasitic capacitance CX is not expressed in
parallel to the electret capacitor EC, but one electrode of the parasitic capacitance CX is
connected to the output terminal of the operational amplifier OP2, and the other electrode is
10-04-2019
7
electret capacitor EC It is shown connected to one of the electrodes.
[0024]
When output signal Vfb is applied to one electrode of parasitic capacitance CX, parasitic
capacitance CX functions as a coupling capacitance to transmit only an AC signal to one
electrode of electret capacitor EC while removing a DC bias component in output signal Vfb. .
Here, the amplification factor of the output signal Vfb with respect to the input signal Vin, that is,
the amplification factor of each voltage signal of the transistor T1 and the operational amplifier
OP2 is adjusted to amplify the value of the AC signal transmitted to one electrode of the electret
capacitor EC. For example, the amplitude value of the voltage between the gate and the source of
the transistor T1 can be made close to the value of the input signal Vin when the parasitic
capacitances CX and CG do not exist. As described above, since the output signal Vfb is a
feedback signal in phase with the input signal Vin, the AC signal transmitted to one electrode of
the electret capacitor EC is also in phase with the input signal Vin, and the potential at one
electrode of the electret capacitor EC It is possible to emphasize the change of Therefore, the
signal between the gate and the source of the transistor T1 which is weak due to the influence of
the parasitic capacitances CX and CG is amplified, and the influence of the parasitic capacitances
CX and CG on the microphone device can be suppressed. That is, the gate-source voltage of the
transistor T1 is increased by providing the output signal Vfb, which is a feedback signal in phase
with the input signal Vin, to one electrode of the parasitic capacitance CX to emphasize the
change in potential at the other electrode. It is possible to suppress the decrease in the sensitivity
of the microphone device MU1 due to the parasitic capacitance CX.
[0025]
If it is possible to adjust the capacitance value of the parasitic capacitance CX, the ratio of the
voltage applied across the parasitic capacitance CX to the voltage applied to the electret
capacitor EC in the output signal Vfb, the electret capacitor EC It is also possible to adjust the
time during which the potential at the one electrode changes.
[0026]
The amplification factor of the voltage signal of both the transistor T1 and the operational
amplifier OP2 corresponds to the value of the input signal Vin when the AC signal transmitted to
one electrode of the electret capacitor EC does not have parasitic capacitances CX and CG. It is
desirable to make adjustments so as not to exceed.
10-04-2019
8
If the alternating current signal exceeds the value of the input signal Vin when the parasitic
capacitances CX and CG do not exist, positive feedback may be generated, and an oscillation
phenomenon may occur to fail to function as a microphone device.
[0027]
If the microphone device MU1 according to the present embodiment is used, an AC signal from
which the DC bias component has been removed from the output signal Vfb by the parasitic
capacitance CX is transmitted to one electrode of the electret capacitor EC. On the other hand,
the input signal Vin generated between the electrodes can be amplified. Thus, the gate-source
voltage of the transistor T1 can be increased, and the decrease in the sensitivity of the
microphone device MU1 due to the parasitic capacitance CX can be suppressed. Further, by
adjusting the capacitance value of the parasitic capacitance CX, it is possible to adjust the
potential at one electrode of the electret capacitor EC and the time of its change.
[0028]
In the present embodiment, MOS transistors are used as the transistors T1 and T2, but of course
bipolar transistors may be used. In the case of using a bipolar transistor, the above gate, drain
and source may be replaced with base, collector and emitter, respectively.
[0029]
Second Preferred Embodiment This preferred embodiment shows a specific structure in the
vicinity of the electret capacitor EC in the microphone device MU1 according to the first
preferred embodiment. FIG. 2 is a cross-sectional view showing the structure. Also in FIG. 2, as in
FIG. 6, the electret capacitor EC includes the wiring film IL2 formed on the semiconductor
substrate SB as one electrode. The wiring film IL2 is formed on the semiconductor substrate SB
via the insulating films IF1 and IF2. In addition, the electret capacitor EC is provided above the
semiconductor substrate SB with a space from the wiring film IL2 as the other electrode of the
electret film EL made of a dielectric in which a fixed amount of electrostatic charge is fixed
semipermanently. The electret film EL is a vibrating film that vibrates by receiving sound
pressure. The ground potential GND is applied to the electret film EL.
10-04-2019
9
[0030]
The semiconductor substrate SB is, for example, a silicon substrate, and in FIG. 6, the
semiconductor substrate SB contains, for example, a P-type impurity. The ground potential GND
is applied to the semiconductor substrate SB. Impurity layers WL1 to WL3 are formed on the
surface of the semiconductor substrate SB by ion implantation or the like. Among these, the Ntype impurity layer WL2 is provided below the wiring film IL2. The P-type impurity layers WL1
and WL3 surround the periphery of the N-type impurity layer WL2 to isolate the elements.
[0031]
A wiring film IL1 which is a wiring connected to the output end of the operational amplifier OP2
is formed on the insulating film IF1. The wiring film IL1 penetrates the insulating film IF1 and is
connected to the N-type impurity layer WL2 on the surface of the semiconductor substrate SB.
Further, in the N-type impurity layer WL2, the contact region CT having a relatively high
impurity concentration is provided in the connection portion with the wiring film IL1 to reduce
the resistance value of the connection portion.
[0032]
An insulating film IF2 is formed to cover the insulating film IF1 and the wiring film IL1. The
insulating films IF1 and IF2 are, for example, an oxide film or a nitride film, and the wiring films
IL1 and IL2 are, for example, conductive films made of Al or the like. Further, an insulating
protective film PF is formed on the upper surfaces of the wiring film IL2 and the insulating film
IF2, and covers these films. Further, the protective film PF is also, for example, an oxide film, a
nitride film or the like.
[0033]
Although not shown in FIG. 2, diodes D1 and D2 and resistors R1 to R3 and transistors T1 and
T2 and operational amplifiers OP1 and OP2 in FIG. 1 are provided in semiconductor substrate SB
around the portion where electret capacitor EC is formed. OP2 is also formed.
10-04-2019
10
[0034]
As described above, when the N-type impurity layer WL2 is provided on the surface of the
semiconductor substrate SB and the output signal Vfb of the operational amplifier OP2 is applied
thereto through the wiring film IL2, conventionally, the wiring film IL2 and the semiconductor
substrate SB The parasitic capacitance CX that has been generated between the above is
generated between the wiring film IL2 and the N-type impurity layer WL2.
Therefore, the parasitic capacitance CX is formed between one electrode of the electret capacitor
EC and the output end of the operational amplifier OP2 as shown in the circuit diagram of FIG.
[0035]
The output signal Vout has a positive DC bias even when the input signal Vin is not input because
the transistor T1 is a depletion type. Therefore, if the value of the constant potential Vref2 is
appropriately set, the output signal Vfb output from the operational amplifier OP2 also becomes
positive. Then, since the potential of the N-type impurity layer WL2 becomes positive and
becomes higher than the potential GND of the semiconductor substrate SB, the reverse bias state
of the PN junction is established between the N-type impurity layer WL2 and the semiconductor
substrate SB, Almost no current flows.
[0036]
When the microphone device according to the present embodiment is used, the N-type impurity
layer WL2 is provided on the surface of the semiconductor substrate SB, and the output signal
Vfb of the operational amplifier OP2 is applied thereto through the wiring film IL2, so that ion
implantation The microphone device MU1 according to the first embodiment can be easily
realized by the semiconductor process.
[0037]
The capacitance value of the parasitic capacitance CX can be adjusted by the film thicknesses and
dielectric constants of the insulating films IF1 and IF2, and the areas of the wiring film IL2 and
the N-type impurity layer WL2.
10-04-2019
11
Therefore, as described in the first embodiment, the ratio of the voltage applied across the
parasitic capacitance CX to the voltage applied to the electret capacitor EC in the output signal
Vfb, the potential at one electrode of the electret capacitor EC, You can also adjust the changing
time of
[0038]
<Third Embodiment> The present embodiment is a modification of the microphone device
according to the second embodiment. FIG. 3 is a cross-sectional view showing the structure. In
FIG. 3, the elements having the same functions as those of the microphone device according to
the second embodiment are denoted by the same reference numerals.
[0039]
In the microphone device according to the present embodiment, the insulating film IF2 is not
formed, and the wiring film IL3 corresponding to the wiring film IL2 is formed on the insulating
film IF1 like the wiring film IL1. As described above, when the wiring film IL3 is formed on the
insulating film IF1 together with the wiring film IL1, the wiring film IL3 and the wiring film IL1
can be formed at one time in the same photolithography process in the manufacturing process of
the microphone device. It will be less. Further, since the insulating film IF2 is also unnecessary,
the cost required for the material can be reduced.
[0040]
The other configuration is the same as the microphone device according to the second
embodiment, and thus the description thereof is omitted.
[0041]
Fourth Preferred Embodiment This preferred embodiment is also a modification of the
microphone device according to the second preferred embodiment.
FIG. 4 is a cross-sectional view showing the structure. In FIG. 4, elements having the same
10-04-2019
12
functions as those of the microphone device according to the second embodiment are denoted by
the same reference numerals.
[0042]
In the microphone device according to the present embodiment, the impurity layers WL1 to WL3
and the contact region CT are not formed, and the wiring film IL4 corresponding to the wiring
film IL1 is formed on the insulating film IF1. However, the wiring film IL4 is formed to extend
below the wiring film IL2, and also functions as one electrode of the parasitic capacitance CX in
place of the N-type impurity layer WL2.
[0043]
As described above, when the wiring film IL4 is formed below the wiring film IL2 and formed on
the insulating film IF1, there is no need to form the impurity layers WL1 to WL3 and the contact
region CT, and the number of processes can be reduced.
[0044]
When N-type impurity layer WL2 is used as one electrode of parasitic capacitance CX as in the
second and third embodiments, a leak current is generated in semiconductor substrate SB and
the potential of N-type impurity layer WL2 becomes unstable. It is conceivable that excessive
power consumption occurs as the output signal Vfb fluctuates because the resistance value of the
N-type impurity layer WL2 is high.
[0045]
However, if the wiring film IL4 functions as one electrode of the parasitic capacitance CX instead
of the N-type impurity layer WL2 as in the present embodiment, the semiconductor substrate SB
has a relatively leak current because it is through the insulating film IF1. When the low
resistance material such as Al is used as the wiring film IL4, excessive power consumption is less
likely to occur with the fluctuation of the output signal Vfb.
[0046]
The other configuration is the same as the microphone device according to the second
embodiment, and thus the description thereof is omitted.
10-04-2019
13
[0047]
According to the first aspect of the present invention, the alternating current signal from which
the DC bias component has been removed from the output of the amplifier by the capacitor is
transmitted to one electrode of the electret capacitor. The amplitude of the voltage generated
between the electrodes can be increased.
Therefore, the decrease in sensitivity of the microphone device can be suppressed.
In addition, by adjusting the capacitance value of the capacitor, it is possible to adjust the
potential at the other electrode of the electret capacitor and the time of its change.
[0048]
According to the second aspect of the present invention, the conductive layer is provided under
the insulating layer to face the other electrode of the electret capacitor, and the output of the
amplifier is given to the conductive layer, so that one electrode of the electret capacitor and the
conductive layer The microphone device according to claim 1 can be realized as a capacitor in
the microphone device according to claim 1.
[0049]
According to the third aspect of the present invention, since the impurity layer is formed on the
surface of the semiconductor substrate below the insulating layer to form the conductive layer,
the conductive layer can be easily formed by a semiconductor process such as ion implantation. .
[0050]
According to the invention of claim 4, since the wiring layer is formed on the insulating layer, the
wiring layer and one electrode of the electret capacitor can be formed at one time in the same
process in the manufacturing process, and the number of processes is small. It is finished.
[0051]
According to the fifth aspect of the present invention, since the conductive layer is formed on the
first insulating film and below the second insulating film, the impurity layer is formed on the
10-04-2019
14
surface of the semiconductor substrate as in the microphone device of the third aspect. There is
no need to do it, and the number of processes is reduced.
In addition, the leakage current does not flow relatively easily because the semiconductor
substrate is through the first insulating film, and if a low resistance material such as Al is used as
the conductive layer, excess power is consumed along with the fluctuation of the output of the
amplifier. Consumption is unlikely to occur.
[0052]
Brief description of the drawings
[0053]
FIG. 1 is a circuit diagram showing a microphone device according to Embodiment 1 of the
present invention.
[0054]
FIG. 2 is a cross-sectional view showing a microphone device according to Embodiment 2 of the
present invention.
[0055]
FIG. 3 is a cross-sectional view showing a microphone device according to Embodiment 3 of the
present invention.
[0056]
FIG. 4 is a cross-sectional view showing a microphone device according to Embodiment 4 of the
present invention.
[0057]
FIG. 5 is a circuit diagram showing a conventional microphone device.
[0058]
6 is a cross-sectional view showing a conventional microphone device.
10-04-2019
15
[0059]
Explanation of sign
[0060]
EC electret capacitor, CG, CX parasitic capacitance, T1, T2 transistor, OP1, OP2 operational
amplifier, EL electret film, IL1, IL2 wiring film, IF1, IF2 insulating film, SB semiconductor
substrate, WL1-WL3 impurity layer.
10-04-2019
16
Документ
Категория
Без категории
Просмотров
0
Размер файла
26 Кб
Теги
description, jp2001231098
1/--страниц
Пожаловаться на содержимое документа