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WO2011111125A1 - Dispositif de traitement de signal et unité de microphone à sortie numérique - Google Patents

Dispositif de traitement de signal et unité de microphone à sortie numérique Download PDF

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Publication number
WO2011111125A1
WO2011111125A1 PCT/JP2010/004936 JP2010004936W WO2011111125A1 WO 2011111125 A1 WO2011111125 A1 WO 2011111125A1 JP 2010004936 W JP2010004936 W JP 2010004936W WO 2011111125 A1 WO2011111125 A1 WO 2011111125A1
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WO
WIPO (PCT)
Prior art keywords
reference voltage
analog
digital
output
microphone
Prior art date
Application number
PCT/JP2010/004936
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English (en)
Japanese (ja)
Inventor
茂雄 政井
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パナソニック株式会社
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Publication date
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Publication of WO2011111125A1 publication Critical patent/WO2011111125A1/fr

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M3/00—Conversion of analogue values to or from differential modulation
    • H03M3/30—Delta-sigma modulation
    • H03M3/322—Continuously compensating for, or preventing, undesired influence of physical parameters
    • H03M3/324—Continuously compensating for, or preventing, undesired influence of physical parameters characterised by means or methods for compensating or preventing more than one type of error at a time, e.g. by synchronisation or using a ratiometric arrangement
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
    • H04R3/06—Circuits for transducers, loudspeakers or microphones for correcting frequency response of electrostatic transducers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M3/00—Conversion of analogue values to or from differential modulation
    • H03M3/30—Delta-sigma modulation
    • H03M3/39—Structural details of delta-sigma modulators, e.g. incremental delta-sigma modulators
    • H03M3/412—Structural details of delta-sigma modulators, e.g. incremental delta-sigma modulators characterised by the number of quantisers and their type and resolution
    • H03M3/422—Structural details of delta-sigma modulators, e.g. incremental delta-sigma modulators characterised by the number of quantisers and their type and resolution having one quantiser only
    • H03M3/43—Structural details of delta-sigma modulators, e.g. incremental delta-sigma modulators characterised by the number of quantisers and their type and resolution having one quantiser only the quantiser being a single bit one
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M3/00—Conversion of analogue values to or from differential modulation
    • H03M3/30—Delta-sigma modulation
    • H03M3/39—Structural details of delta-sigma modulators, e.g. incremental delta-sigma modulators
    • H03M3/436—Structural details of delta-sigma modulators, e.g. incremental delta-sigma modulators characterised by the order of the loop filter, e.g. error feedback type
    • H03M3/456—Structural details of delta-sigma modulators, e.g. incremental delta-sigma modulators characterised by the order of the loop filter, e.g. error feedback type the modulator having a first order loop filter in the feedforward path
    • 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
    • H04R19/04—Microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/003—Mems transducers or their use

Definitions

  • the present invention relates to a signal processing device and a digital output microphone unit including the same.
  • a microphone is a sensor that converts sound (elastic wave propagating through an elastic body) into an analog electric signal, and is classified into a piezoelectric type, an electrodynamic type, an electrostatic type, and the like depending on the conversion method.
  • electrostatic ECM Electrostatic Condenser Microphone
  • MEMS Micro Electro Mechanical Systems
  • Patent Document 1 discloses an ECM configured by laminating three members, an electric circuit board, a back electrode board, and a diaphragm support frame, in which an electrode film, an electret layer, a diaphragm, and the like are integrated. In this way, by using the same material for the three members, the acoustic characteristics are improved with respect to ambient temperature changes.
  • Patent Document 2 discloses a microphone unit that incorporates a thermistor and adjusts an output level following a change in ambient temperature.
  • FIG. 18 is a circuit diagram showing the configuration of the conventional microphone unit shown in FIGS.
  • a microphone unit 50 shown in FIG. 18 includes a microphone 51 and a preamplifier 52 including an operational amplifier 53.
  • the output of the microphone 51 is connected to the non-inverting input terminal of the operational amplifier 53.
  • the output of the operational amplifier 53 is connected to an output terminal 55 for extracting an audio signal, and is also connected to an inverting input terminal of the operational amplifier 53 via a feedback resistor 56.
  • the inverting input terminal of the operational amplifier 53 is connected to a predetermined terminal 59 via a variable resistor 58 for determining the gain of the preamplifier 52 as with the feedback resistor 56.
  • a signal line from the thermistor 57 is connected to both ends of the feedback resistor 56, whereby the operational amplifier 53 for determining the gain (amplification factor) of the preamplifier 52 is connected.
  • a feedback resistance element is configured. With this configuration, when the ambient temperature increases, the resistance value of the thermistor 57 connected in parallel to the feedback resistor 56 decreases, and the gain of the preamplifier 52 is automatically adjusted so as to suppress the increase in sensitivity of the microphone unit 50 due to the temperature increase. Adjusted.
  • the resistance value of the thermistor 57 is increased, and the gain of the preamplifier 52 is automatically adjusted so as to suppress the decrease in sensitivity of the microphone unit 50 due to the temperature decrease.
  • the initial sensitivity of the microphone unit 50 is adjusted in advance in the manufacturing stage or the like so as to be within the specified sensitivity range at room temperature by the variable resistor 58.
  • the temperature characteristics of the microphone unit 50 are adjusted by the resistance values of the variable resistor 58 and the thermistor 57.
  • Patent Documents 1 and 2 have the following problems.
  • Patent Document 1 In the technique described in Patent Document 1, it is expected to improve acoustic characteristics against changes in ambient temperature by using the same material for the three members of the electric circuit board, the back electrode board, and the diaphragm support frame. However, it is not clear how much it has actually been improved, and there is a problem of lack of concreteness and feasibility. Further, when the same material is used for the three members, the analog electric signal output from the ECM still changes with respect to the ambient temperature change. However, Patent Document 1 discloses that the temperature characteristics of the analog electric signal are improved. There is no description or suggestion of a specific configuration for this purpose.
  • a variable resistor 58 is built in the microphone unit 50 in advance in consideration of the variation of the microphone itself caused by the manufacturing process, and the initial sensitivity of the microphone unit 50 is a specified sensitivity at normal temperature in the manufacturing stage. It is adjusted in advance by the variable resistor 58 so as to be within the range.
  • the adjustment of the initial sensitivity is complicated, and there is a problem that the manufacturing cost is increased by the steps required for the adjustment.
  • Patent Document 2 in order to adjust the gain of the preamplifier 52 in order to improve the temperature characteristic of the output (analog electric signal) of the microphone unit 50, two or more types of resistors (feedback resistor 56, thermistor 57) that are not of the same type are used.
  • the variable resistor 58 is built in the microphone unit 50. Since these resistors have individual temperature characteristic variations, there is a problem that uniform adjustment is difficult and difficult for the gain of the preamplifier 52 and the temperature characteristic of the output of the microphone unit 50. .
  • the peripheral circuit including the preamplifier 52 of the microphone unit 50 is integrated, the temperature characteristics of two or more types of resistors that are not of the same type in the integrated circuit vary significantly. It becomes even more prominent.
  • Patent Documents 1 and 2 describe nor suggest that a microphone unit including a microphone is miniaturized and digitized.
  • the microphone unit is generally composed of discrete components, it has been difficult to reduce the size of the microphone unit.
  • the number of new parts increases for digitization, and thus the digital output microphone unit is more difficult to downsize.
  • the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a digital output microphone unit that stabilizes digital output fluctuations with respect to ambient temperature changes within a wide temperature range.
  • a signal processing device is a signal processing device that performs analog-to-digital conversion of an analog electric signal converted from sound by a microphone into a digital electric signal, and outputs the digital electric signal.
  • a preamplifier for amplifying the output analog electric signal; an analog-to-digital converter for converting the analog electric signal output from the preamplifier to a digital electric signal by comparing with a reference voltage; and generating the reference voltage to generate the analog
  • a reference voltage generating circuit for supplying to the digital converter, wherein the reference voltage generating circuit is a temperature of its electrical properties compared to other electric circuit elements among the electric circuit elements constituting the signal processing device.
  • the analog-to-digital converter outputs the analog electrical signal output from the preamplifier. Since the signal is compared with this reference voltage, even if the magnitude of the analog electrical signal converted from sound by the microphone changes depending on the ambient temperature change, this reference voltage will change to the magnitude of the analog electrical signal.
  • the high temperature dependent element is a diode
  • the reference voltage generation circuit is configured by connecting a current source and the diode in series between a power supply terminal and a ground terminal, The reference voltage may be generated based on a voltage at a connection point between a power supply terminal and the diode.
  • the temperature characteristic of the diode is approximated as a linear line similarly to the temperature characteristic of the microphone, and the forward voltage of the diode is stable at about 0.7 V. Therefore, output from the microphone is achieved by using the diode. Therefore, it is possible to easily generate a reference voltage having a temperature characteristic that cancels the temperature characteristic of the analog electric signal. Further, it is possible to manufacture the reference voltage generation circuit with a small number of parts.
  • the high temperature dependent element is a resistor having a positive or negative temperature coefficient
  • the reference voltage generating circuit includes a current source and the resistor in series between a power supply terminal and a ground terminal.
  • the reference voltage may be generated based on a voltage at a connection point between the power supply terminal and the resistor. According to this configuration, the reference voltage can be easily given temperature characteristics as in the case of the diode, and the reference voltage generation circuit can be manufactured with a small number of components.
  • the preamplifier, the analog-digital converter, and the reference voltage generation circuit may be integrated. According to this configuration, a very small and accurate digital output microphone unit can be realized.
  • the digital output microphone unit includes a microphone that converts sound into an analog electrical signal, a preamplifier that amplifies the analog electrical signal output from the microphone, and an analog electrical signal output from the preamplifier as a reference voltage.
  • An analog-to-digital converter that converts the signal into a digital electric signal, and a reference voltage generation circuit that generates the reference voltage and supplies the reference voltage to the analog-to-digital converter.
  • the electric circuit element includes an element having a higher temperature dependency of its electrical properties than the other electric circuit elements (hereinafter referred to as a high temperature dependent element). A reference voltage corresponding to the voltage between both terminals is generated.
  • the microphone may be an ECM (Electret Condenser Microphone).
  • This configuration can realize an ECM unit with a temperature compensation function.
  • the microphone may be a MEMS (Micro Electro Mechanical Systems) microphone.
  • the analog-to-digital converter may be a delta-sigma modulation type analog-to-digital converter. According to this configuration, it is possible to provide a high-quality digital output microphone unit with low noise.
  • the digital electric signal may be converted into a PDM (Pulse Density Modulation) method and output to the outside.
  • PDM Pulse Density Modulation
  • the signal output from the digital output microphone unit is a digital electric signal, it is difficult to be affected by disturbance noise, and location-free can be realized in a set product on which the digital output microphone unit is mounted.
  • the present invention includes a microphone, a preamplifier, and an analog-digital converter.
  • An analog electrical signal output from the microphone is input to the analog-digital converter via the preamplifier, and the analog-digital conversion is performed.
  • the digital output microphone unit that converts it into a digital electric signal by the device is the application target.
  • the digital electrical signal output from the digital output microphone unit has the same temperature characteristics as the analog electrical signal output from the conventional analog output microphone unit. Therefore, the present inventor has considered that a temperature characteristic having a temperature dependence opposite to the original temperature characteristic is created inside the digital output microphone unit and used to cancel the original temperature characteristic.
  • a reference voltage to be compared with an analog electric signal having a temperature characteristic in an analog-digital converter has a temperature characteristic having a temperature dependency similar to the temperature characteristic of the analog electric signal. “Having opposite temperature dependence” means “the sign of the temperature coefficient is opposite”, and “similar temperature dependence” means “the sign of the temperature coefficient is the same”. To do.
  • analog-digital converter the basic principle of the analog-digital converter is that the analog electric signal is quantized by comparing the reference voltage of the analog-digital converter with the analog electric signal input to the analog-digital converter. Is to do. If this analog-digital conversion process is simplified, it can be expressed by the following equation.
  • Dcode (Vin / Vref) ⁇ 2 N
  • Vin an input voltage (analog electric signal)
  • Vref a reference voltage of the analog-digital converter
  • N a conversion bit number (conversion resolution).
  • Vin 1V
  • Vref 1V
  • N 5
  • Vin 0.5V
  • Vref 1V
  • N 5
  • the digital output code Dcode outputs “01111” of 1 ⁇ 2 full scale. That is, when the reference voltage Vref is constant, it can be seen that the digital output code Dcode varies greatly according to the variation of the input voltage Vin.
  • the temperature change of the analog electric signal input to the analog-to-digital converter even if the magnitude of the analog electric signal input from the microphone to the analog-to-digital converter via the preamplifier changes due to a change in ambient temperature, the temperature change of the analog electric signal input to the analog-to-digital converter.
  • a reference voltage that follows the change due to is generated, and the reference voltage is used as a reference voltage of the analog-digital converter.
  • the digital output code Dcode is stabilized without depending on the ambient temperature change.
  • an element (hereinafter referred to as a high temperature dependent element) having a higher temperature dependence of its electrical properties (electrical resistance, resistivity, conductivity, etc.) A reference voltage corresponding to the voltage between both terminals of the element is generated.
  • a high temperature dependent element By adopting this high temperature dependent element, it becomes easy to give temperature characteristics to the reference voltage of the analog-digital converter. Further, it is sufficient to use only the high temperature dependent element when generating the reference voltage, and there is no need to combine different types of electric circuit elements as in the thermistor 57 and the feedback resistor 56 shown in FIG. . For this reason, it is only necessary to consider the manufacturing variation of the high temperature dependent element, and it becomes easy to generate a desired reference voltage that follows the change of the analog electric signal output from the microphone due to the temperature.
  • examples of the high temperature-dependent element include a diode (including a diode-connected MOSFET and a bipolar transistor) described later, and a resistor having a positive or negative temperature coefficient (polysilicon resistor, diffused resistor, etc.).
  • the temperature characteristic of the diode is approximated as a linear line having a positive or negative temperature coefficient similar to the temperature characteristic of the microphone, and the forward voltage of the diode is stable at about 0.7 V at room temperature. For example, it becomes easy to generate a reference voltage that follows changes in temperature of an analog electrical signal output from a microphone. It is also possible to manufacture the reference voltage generation circuit with a small number of parts. The same can be said when a resistor approximating the temperature characteristic of the diode is used.
  • FIG. 1 is a circuit diagram showing a configuration of a digital output microphone unit according to the first embodiment of the present invention.
  • the digital output microphone unit 100 shown in FIG. 1 includes a microphone 1, a preamplifier 15, an analog-digital converter 12, and a reference voltage generator in a casing 18 provided with an opening 11 for collecting ambient sounds.
  • the circuit 14 is configured in combination.
  • the digital output microphone unit 100 includes at least a power supply terminal 2, a ground terminal 9, and a digital output terminal 16 as external terminals.
  • the microphone 1 is a sound detection sensor that converts sound collected from the opening 11 (elastic wave propagating through the elastic body) into an analog electric signal.
  • the microphone 1 is preferably an electrostatic ECM (Electret Condenser Microphone) or MEMS (Micro Electro ⁇ ⁇ ⁇ ⁇ Mechanical Systems) microphone in consideration of miniaturization of the digital output microphone unit 100 and integration of an integrated circuit. It may be a mold or an electrodynamic type.
  • the preamplifier 15 is an amplifier that receives an analog electrical signal output from the microphone 1 and amplifies the analog electrical signal with a predetermined amplification factor in order to adjust the sound quality, volume, and the like.
  • the analog-digital converter 12 receives the analog electric signal output from the preamplifier 15 and converts the analog electric signal into a digital electric signal based on a comparison between the analog electric signal and a reference voltage Vref described later. An output of the analog-digital converter 12 is connected to a digital output terminal 16, and a digital electric signal is output to the outside through the digital output terminal 16.
  • the analog-digital converter 12 is provided with a reference voltage input terminal 17 to which the reference voltage Vref generated by the reference voltage generation circuit 14 is applied.
  • the analog-digital converter 12 is preferably a delta-sigma modulation type that can obtain high resolution.
  • FIG. 2 is a circuit diagram showing a configuration of a delta-sigma modulation type analog-digital converter.
  • the analog-digital converter 12 shown in the figure includes a delta-sigma modulator constituted by a subtractor 121, an integrator 122, a comparator (quantizer) 123, a delay unit 124, and a digital-analog converter 125, and a digital And a filter 126.
  • a delta-sigma modulator constituted by a subtractor 121, an integrator 122, a comparator (quantizer) 123, a delay unit 124, and a digital-analog converter 125, and a digital And a filter 126.
  • an analog electric signal is input to the subtractor 121 together with the output at the previous time of the digital-analog converter 125.
  • the subtractor 121 calculates a difference between the analog electric signal and the output of the digital-analog converter 125 and inputs the difference to the integrator 122.
  • the integrator 122 inputs the result of adding the output of the subtractor 121 and the data at the previous time of the output to the comparator 123.
  • the comparator 123 compares the output of the integrator 122 and the reference voltage Vref applied to the reference voltage input terminal 17 to generate a digital electric signal.
  • the digital electric signal output from the comparator 123 is oversampled by a latch circuit (not shown) and the like and then input to the digital filter 126 and is fed back to the subtractor 121 via the delay device 124 and the digital-analog converter 125. Entered.
  • the digital filter 126 performs an averaging process and decimation of the sampling frequency to improve the resolution of the oversampled digital electrical signal.
  • the analog-to-digital converter 12 can achieve a high signal-to-noise ratio with low power consumption by using a 4th-order delta-sigma modulation type with a clock frequency of 1 M to 4 MHz and an oversampling rate of 50 to 64 times.
  • the high-quality digital output microphone unit 100 can be realized.
  • the analog-to-digital converter 12 is not limited to the delta-sigma modulation type, and any analog-to-digital converter may be used as long as the analog electric signal output from the preamplifier 15 is compared with the reference voltage Vref. For example, a successive approximation type, a flash type, or a pipeline type may be used.
  • the digital electric signal output from the analog-digital converter 12 is preferably output to the outside from the digital output terminal 16 after being converted into PDM (Pulse Density Modulation) format.
  • a DSP Digital Signal Processor
  • a digital electric signal may be output from the digital output terminal 16 according to the audio interface format by taking the DSP into the housing 18.
  • the preamplifier 15, the analog-digital converter 12, and the reference voltage generation circuit 14 are preferably configured as an integrated circuit signal processing device 13 instead of being configured as discrete components.
  • the power supply terminal 2 and the ground terminal 9 can be shared among the preamplifier 15, the analog-digital converter 12, and the reference voltage generation circuit 14, and further miniaturization of the digital output microphone unit 100 can be realized. .
  • FIG. 3 is a circuit diagram showing a configuration of a reference voltage generation circuit in the digital output microphone unit of FIG.
  • the reference voltage generation circuit 14 shown in the figure includes a current source 19 and a diode 25 connected in series between a power supply 27 and a ground terminal, and an inverting amplifier 23 to which a voltage at a connection point between the current source 19 and the diode 25 is input. And is composed of.
  • the current source 19 has an input side connected to the power source 27 and supplies a forward current to the diode 25. Note that the current value of the current source 19 preferably does not change due to changes in temperature and power supply voltage.
  • the diode 25 has its cathode side connected to the ground terminal and its anode side connected to the inverting input terminal of the operational amplifier 26 via the output of the current source 19 and the input resistor 20. That is, the anode-cathode voltage of the diode 25 is applied to the inverting input terminal of the operational amplifier 26.
  • the output terminal of the operational amplifier 26 is connected to the reference voltage output terminal 22 and is connected to the inverting input terminal of the operational amplifier 26 via the feedback resistor 21 that determines the gain of the inverting amplifier 23.
  • the input resistor 20 and the feedback resistor 21 are preferably manufactured using the same type of manufacturing process technology. As a result, variations in resistance values of the input resistor 20 and the feedback resistor 21 can be reduced, and variations in gain of the inverting amplifier 23 can be reduced.
  • the non-inverting input terminal of the operational amplifier 26 is connected to the power source 24 and controls the output voltage of the inverting amplifier 23. It is preferable that the voltage value of the power supply 24 does not change due to changes in temperature and power supply voltage.
  • FIG. 4 is a graph showing temperature characteristics of an ECM output signal (analog electrical signal) having a positive temperature coefficient in the digital output microphone unit shown in FIG. The graph is obtained when the ECM collects a sound corresponding to 94 dB SPL (Sound Pressure Level).
  • the voltage level of the output signal of the ECM is about 20 mVpp (Peak to Peak) at 27 ° C., but decreases to about 16 mVpp (Peak to Peak) at ⁇ 40 ° C., and about 25 mVpp at 90 ° C. It can be seen that the number has increased.
  • the temperature characteristic of the ECM is approximated as a linear line (or a linear curve) having a positive slope.
  • FIG. 5 is a graph showing the temperature characteristics of the anode-cathode voltage of the diode in the digital output microphone unit shown in FIG.
  • the slope of the anode-cathode voltage with respect to the temperature change is about ⁇ 2 (mV / ° C.).
  • the gain of the inverting amplifier 23, that is, the ratio between the input resistor 20 and the feedback resistor 21 is set to “1”, for example, the gradient of the temperature characteristic of the output voltage (reference voltage Vref) of the reference voltage generation circuit 14 is about +2. (MV / ° C.). Therefore, similar to the temperature characteristic of the microphone shown in FIG. 4, the temperature characteristic of the reference voltage Vref is approximated as a linear line having a positive slope. Note that the ratio between the input resistor 20 and the feedback resistor 21 for determining the gain may be determined so as to correspond to the temperature change of the analog electric signal output from the microphone 1.
  • FIG. 6 is a graph showing the temperature characteristics of the output level (digital electric signal) of the digital output microphone unit shown in FIG. The graph is obtained when an ECM having a positive temperature coefficient collects a sound equivalent to 94 dB SPL.
  • the broken line indicates the output level when the reference voltage Vref is assumed to be constant, and the solid line indicates the output level when the reference voltage Vref is generated based on the anode-cathode voltage of the diode 25.
  • FIG. 7 is a circuit diagram showing a configuration of a reference voltage generation circuit in the digital output microphone unit according to the second embodiment of the present invention.
  • a diode 25 and a current source 19 connected in series between a power supply 27 and a ground terminal, and a non-inverted input of a voltage at a connection point between the diode 25 and the current source 19. And an amplifier 28.
  • the anode side of the diode 25 is connected to the power source 27, and the cathode side is connected to the input of the current source 19.
  • the voltage at the connection point between the diode 25 and the current source 19 is connected to the inverting input terminal of the operational amplifier 26.
  • the output terminal of the operational amplifier 26 is connected to the reference voltage output terminal 22 and is connected to the inverting input terminal of the operational amplifier 26 via a feedback resistor 29 that determines a gain (amplification factor).
  • the inverting input terminal of the operational amplifier 26 is connected to the power source 24 via a resistor 30 that determines the gain of the non-inverting amplifier 28.
  • the feedback resistor 29 and the resistor 30 can be manufactured using the same manufacturing process technology of the same type, so that variations in the resistance values of the feedback resistor 29 and the resistor 30 can be reduced, and gain variations in the non-inverting amplifier 28 can be reduced. Can be reduced. Further, it is preferable that the voltage value of the power supply 24 does not change due to changes in temperature and power supply voltage.
  • the slope of the temperature characteristic of the output voltage (reference voltage Vref) of the reference voltage generation circuit 14 is controlled using the slope (mV / ° C.) of the temperature characteristic of the anode-cathode voltage of the diode 25. It becomes possible to do.
  • fluctuations in the output level (digital electrical signal) of the digital output microphone unit 100 with respect to ambient temperature changes can be compensated for within a wide temperature range.
  • the gain of the non-inverting amplifier 28 (that is, the ratio of the feedback resistor 29 and the resistor 30) is set so that the temperature characteristic of the anode-cathode voltage of the diode 25 is preserved in the output voltage.
  • FIG. 8 is a circuit diagram showing a configuration of a reference voltage generation circuit in the digital output microphone unit according to the third embodiment of the present invention.
  • FIG. 9 is a graph showing a temperature characteristic of a resistor having a positive temperature coefficient in the digital output microphone unit according to the third embodiment of the present invention.
  • the reference voltage generation circuit 14 shown in FIG. 8 includes a current source 19 and a resistor 31 having a positive temperature coefficient as shown in FIG. And a non-inverting amplifier 28 to which the voltage at the connection point of the resistor 31 is input.
  • the resistor 31 is, for example, a polysilicon resistor or a diffused resistor. One terminal is connected to the ground terminal, and the other terminal is connected to the output of the current source 19 and the non-inverting input terminal of the operational amplifier 26.
  • the output terminal of the operational amplifier 26 is connected to the inverting input terminal of the operational amplifier 26 via a feedback resistor 29 that determines the gain (amplification factor).
  • the inverting input terminal of the operational amplifier 26 is connected to the power supply 24 via a resistor 30 that determines the gain of the non-inverting amplifier 28.
  • the inclination of the temperature characteristic of the resistor 31 similar to the temperature characteristic (primary line) of the microphone 1 (mV / ° C.) is used to increase or decrease the inclination of the temperature characteristic of the output voltage of the reference voltage generation circuit 14. It becomes possible to adjust.
  • fluctuations in the output level (digital electrical signal) of the digital output microphone unit 100 with respect to ambient temperature changes can be compensated for within a wide temperature range.
  • the gain of the non-inverting amplifier 28 (that is, the ratio of the feedback resistor 29 and the resistor 30) is set to the output signal of the microphone 1 so that the temperature characteristic of the resistor 31 having a positive temperature coefficient is stored in the output voltage.
  • FIG. 10 is a circuit diagram showing a configuration of the reference voltage generation circuit 14 in the digital output microphone unit according to the fourth embodiment of the present invention.
  • FIG. 11 is a graph showing a temperature characteristic of a resistor having a negative temperature coefficient in the digital output microphone unit according to the fourth embodiment of the present invention.
  • a reference voltage generation circuit 14 shown in FIG. 10 includes a current source 19 connected in series between a power supply 27 and a ground terminal, a resistor 32 having a negative temperature coefficient as shown in FIG.
  • the operational amplifier 33 is supplied with the voltage at the connection point 32, and the inverting amplifier 23 is supplied with the output of the operational amplifier 33.
  • the resistor 32 is, for example, a polysilicon resistor or a diffused resistor. One terminal is connected to the ground terminal, and the other terminal is connected to the output of the current source 19 and the non-inverting input terminal of the operational amplifier 33.
  • the output terminal of the operational amplifier 33 is connected to the inverting input terminal of the operational amplifier 33.
  • the operational amplifier 33 functions as a backflow prevention buffer (voltage follower) having a gain of “1”.
  • the output terminal of the operational amplifier 33 is connected to the inverting input terminal of the operational amplifier 26 through the input resistor 20.
  • the output terminal of the operational amplifier 26 is connected to the inverting input terminal of the operational amplifier 26 via the feedback resistor 21 that determines the gain of the inverting amplifier 23.
  • the temperature of the output voltage of the reference voltage generation circuit 14 is obtained using the gradient (mV / ° C.) of the temperature characteristic of the resistor 32 having a negative temperature coefficient similar to the temperature characteristic (primary line) of the microphone 1. It becomes possible to control the magnitude of the slope of the characteristic.
  • fluctuations in the output level (digital electrical signal) of the digital output microphone unit 100 with respect to ambient temperature changes can be compensated for within a wide temperature range.
  • the gain of the inverting amplifier 23 that is, the ratio between the input resistor 20 and the feedback resistor 21
  • the gain of the inverting amplifier 23 is set to the output signal of the microphone 1 so that the temperature characteristic of the resistor 32 having a negative temperature coefficient is stored in the output voltage. What is necessary is just to determine so that it may respond to the temperature change of an analog electric signal.
  • FIG. 12 is a graph showing temperature characteristics of an ECM output signal (analog electric signal) in the digital output microphone unit according to the fifth embodiment of the present invention. The graph is obtained when an ECM having a negative temperature coefficient collects a sound equivalent to 94 dB SPL.
  • the voltage level of the output signal of the ECM is about 20 mVpp at 27 ° C., but increases to about 25 mVpp at ⁇ 40 ° C. and decreases to about 16 mVpp at 90 ° C.
  • FIG. 13 is a circuit diagram showing a configuration of a reference voltage generation circuit in the digital output microphone unit according to the fifth embodiment of the present invention.
  • the reference voltage generation circuit 14 includes a current source 19 and a diode 25 and a non-inverting amplifier 28 connected in series between a power supply 27 and a ground terminal.
  • the diode 25 has its cathode side connected to the ground terminal, and its anode side connected to the output of the current source 19 and the non-inverting input terminal of the operational amplifier 26.
  • the output terminal of the operational amplifier 26 is connected to the inverting input terminal of the operational amplifier 26 via a feedback resistor 29 that determines the gain (amplification factor) of the non-inverting amplifier 28.
  • the inverting input terminal of the operational amplifier 26 is connected to the power supply 24 via a resistor 30 that determines the gain of the non-inverting amplifier 28.
  • FIG. 14 is a graph showing the temperature characteristic of the output level (digital electric signal) of the digital output microphone unit according to the fifth embodiment of the present invention.
  • the graph is obtained when the ECM collects 94 dB SPL equivalent.
  • the broken line indicates the output level when the reference voltage Vref is constant, and the solid line indicates the output level when the reference voltage Vref is generated based on the anode-cathode voltage of the diode 25.
  • FIG. 15 is a circuit diagram showing a configuration of a reference voltage generation circuit in the digital output microphone unit according to the sixth embodiment of the present invention.
  • the reference voltage generation circuit 14 shown in FIG. 1 includes a diode 25 and a current source 19 connected in series between a power supply 27 and a ground terminal, and an inverting amplifier 23.
  • the reference voltage generation circuit 14 shown in FIG. 1 includes a diode 25 and a current source 19 connected in series between a power supply 27 and a ground terminal, and an inverting amplifier 23.
  • the reference voltage generation circuit 14 shown in FIG. 1 includes a diode 25 and a current source 19 connected in series between a power supply 27 and a ground terminal, and an inverting amplifier 23.
  • the anode side of the diode 25 is connected to the power source 27, and the cathode side thereof is connected to the inverting input terminal of the operational amplifier 26 through the input of the current source 19 and the input resistor 20.
  • the output terminal of the operational amplifier 26 is connected to the inverting input terminal of the operational amplifier 26 via the feedback resistor 21 that determines the gain of the inverting amplifier 23.
  • FIG. 16 is a circuit diagram showing a configuration of a reference voltage generation circuit in the digital output microphone unit according to the seventh embodiment of the present invention.
  • a reference voltage generation circuit 14 shown in FIG. 16 includes a current source 19 connected in series between a power supply 27 and a ground terminal, a resistor 31 having a positive temperature coefficient as shown in FIG. 9, an inverting amplifier 23, It is constituted by.
  • the resistor 31 has one terminal connected to the ground terminal, and the other terminal connected to the output of the current source 19 and the non-inverting input terminal of the operational amplifier 33.
  • the output terminal of the operational amplifier 33 is connected to the inverting input terminal of the operational amplifier 33.
  • the operational amplifier 33 functions as a backflow prevention buffer (voltage follower) having a gain of “1”.
  • the output terminal of the operational amplifier 33 is connected to the inverting input terminal of the operational amplifier 26 through the input resistor 20.
  • the output terminal of the operational amplifier 26 is connected to the inverting input terminal of the operational amplifier 26 via the feedback resistor 21 that determines the gain of the inverting amplifier 23.
  • FIG. 17 is a circuit diagram showing a configuration of a reference voltage generation circuit in the digital output microphone unit according to the eighth embodiment of the present invention.
  • a reference voltage generation circuit 14 shown in FIG. 17 includes a current source 19 connected in series between a power supply 27 and a ground terminal, a resistor 32 having a negative temperature coefficient as shown in FIG. , Is composed of.
  • the resistor 32 has one terminal connected to the ground terminal, and the other terminal connected to the output of the current source 19 and the non-inverting input terminal of the operational amplifier 26.
  • the output terminal of the operational amplifier 26 is connected to the inverting input terminal of the operational amplifier 26 via a feedback resistor 29 that determines the gain (amplification factor).
  • the inverting input terminal of the operational amplifier 26 is connected to the power supply 24 via a resistor 30 that determines the gain of the non-inverting amplifier 28.
  • the present invention is useful for a digital output microphone unit that needs to stabilize a change in digital output level with respect to a change in ambient temperature within a wide temperature range.
  • DESCRIPTION OF SYMBOLS 100 ... Digital output microphone unit 11 ... Opening part 12 ... Analog-digital converter 121 ... Subtractor 122 ... Integrator 123 ... Comparator 124 ... Delay device 125 ... Analog converter 125 ... Digital filter 13 ... Signal processing device 14 ... Reference voltage Generation circuit 15 ... preamplifier 16 ... digital output terminal 17 ... reference voltage input terminal 18 ... housing 19 ... current source 2 ... power supply terminal 9 ... ground terminal 20 ... input resistor 21 ... feedback resistor 22 ... reference voltage output terminal 23 ... inverting amplifier 24 ... power source 25 ... diode 26 ... operational amplifier 27 ... power source 28 ... non-inverting amplifier 29 ... feedback resistor 30 ... resistor 31 ... resistor 32 having a positive temperature coefficient ... resistor 33 having a negative temperature coefficient ... operational amplifier

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Theoretical Computer Science (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Analogue/Digital Conversion (AREA)

Abstract

L'invention porte sur un dispositif de traitement de signal (13) qui effectue une conversion analogique-numérique de signaux électriques analogiques obtenus par conversion du son par un microphone (1) et qui émet des signaux électriques numériques, le dispositif étant pourvu d'un préamplificateur (15) pour amplifier les signaux électriques analogiques émis par le microphone (1), d'un convertisseur analogique-numérique (12) pour comparer les signaux électriques analogiques émis par le préamplificateur (15) à une tension de référence (Vref) et pour effectuer une conversion analogique-numérique, et d'un circuit de génération de tension de référence (14) pour générer la tension de référence (Vref) et pour fournir la tension au convertisseur analogique-numérique (12), le circuit de génération de tension de référence (14) étant pourvu d'un élément qui est davantage dépendant de la température en termes de propriété électrique, par comparaison à d'autres éléments de circuit électrique parmi les éléments de circuit électrique constituant le dispositif de traitement de signal (13), et générant une tension de référence (Vref) qui correspond à la tension entre les bornes de l'élément.
PCT/JP2010/004936 2010-03-12 2010-08-05 Dispositif de traitement de signal et unité de microphone à sortie numérique WO2011111125A1 (fr)

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JP2010056470A JP2011193144A (ja) 2010-03-12 2010-03-12 信号処理装置、デジタル出力マイクロホンユニット
JP2010-056470 2010-03-12

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EP2337226A3 (fr) * 2009-12-18 2012-05-23 Sanyo Electric Co., Ltd. Circuit de traitement de signal
CN104284289A (zh) * 2013-07-12 2015-01-14 英飞凌科技股份有限公司 用于麦克风放大器的系统和方法
EP3480569A1 (fr) * 2017-11-07 2019-05-08 Yamaha Corporation Dispositif de sortie sonore et instrument de musique
CN110554792A (zh) * 2018-06-04 2019-12-10 北京钛方科技有限责任公司 传感器校准调节装置及方法

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JP2013058915A (ja) * 2011-09-08 2013-03-28 Toshiba Corp デジタル信号生成回路及びデジタルマイク
US8699189B2 (en) * 2012-05-22 2014-04-15 Honeywell International Inc. High precision clipping regulator circuit
US9357295B2 (en) 2013-10-22 2016-05-31 Infineon Technologies Ag System and method for a transducer interface
CN111417053B (zh) * 2020-03-10 2023-07-25 北京小米松果电子有限公司 拾音音量控制方法、装置以及存储介质

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Cited By (7)

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Publication number Priority date Publication date Assignee Title
EP2337226A3 (fr) * 2009-12-18 2012-05-23 Sanyo Electric Co., Ltd. Circuit de traitement de signal
US8693707B2 (en) 2009-12-18 2014-04-08 Semiconductor Components Industries, Llc Signal processing circuit
CN104284289A (zh) * 2013-07-12 2015-01-14 英飞凌科技股份有限公司 用于麦克风放大器的系统和方法
EP3480569A1 (fr) * 2017-11-07 2019-05-08 Yamaha Corporation Dispositif de sortie sonore et instrument de musique
CN109756819A (zh) * 2017-11-07 2019-05-14 雅马哈株式会社 传感器输出装置、音响输出装置及乐器
US10659888B2 (en) 2017-11-07 2020-05-19 Yamaha Corporation Sensor output device, sound output device, and musical instrument
CN110554792A (zh) * 2018-06-04 2019-12-10 北京钛方科技有限责任公司 传感器校准调节装置及方法

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