WO2017143177A1

WO2017143177A1 - Microphone memory

Info

Publication number: WO2017143177A1
Application number: PCT/US2017/018353
Authority: WO
Inventors: George FOLSOM; Andrzej Pawlowski
Original assignee: Knowles Electronics, Llc
Priority date: 2016-02-17
Filing date: 2017-02-17
Publication date: 2017-08-24

Abstract

Microphone assemblies, acoustic signal processing circuits, and related methods are provided. One method is implemented in a microphone assembly including a MEMS transducer and processing circuitry disposed in a housing formed by a cover and a base with a conductive pad. The processing circuitry includes memory storing microphone characterization information. The method includes receiving, via the conductive pad of the microphone assembly, a request for the microphone characterization information stored in the memory and transmitting, from the microphone assembly, the microphone characterization information via the conductive pad in response to the request. The microphone characterization information is indicative of a frequency response characteristic of the microphone assembly.

Description

MICROPHONE MEMORY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority to U.S. Provisional Application No. 62/296,270 filed February 17, 2016, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This application relates to microphones and, more specifically to memories in these devices.

BACKGROUND

[0003] Different types of acoustic devices have been used through the years. One type of device is a microphone. In a microelectromechanical system (MEMS) microphone assembly or package, a MEMS die or transducer is used and includes at least one diaphragm and at least one back plate. The MEMS die is supported by a substrate and enclosed by a housing (e.g., a cup or cover with walls). A port may extend through the substrate (for a bottom port device) or through the top of the housing (for a top port device). In any case, sound energy traverses through the port, moves the diaphragm and creates a changing potential of the back plate, which creates an electrical signal. Microphones are deployed in various types of products such as personal computers or cellular phones.

[0004] When placed in these consumer products, the microphones send sensed sound data to other electronics devices deployed within these products, and these devices implement various algorithms. These algorithms utilize microphone parameters such as sensitivity. Typically, the consumer programs their electronics device from a data sheet with specific microphone parameters. Because these parameters are fixed and cannot be changed after the initial programming is performed, this sometimes limits the effectiveness of the algorithms.

[0005] The limitations of previous approaches have resulted in some user dissatisfaction with the previous approaches. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings.

[0007] FIG. 1 is a side cutaway view of one example of a microphone.

[0008] FIG. 2 is a block diagram of an integrated circuit.

[0009] FIG. 3 is a call flow diagram showing communication between a customer electronics device and a memory in a microphone.

[0010] FIG. 4 is a diagram showing the use of a code and look-up table.

[0011] FIG. 5 is a diagram showing an example of an interface between a microphone and an electronics device.

[0012] FIG. 6 is a diagram showing an example of an interface between a microphone and an electronics device.

[0013] FIG. 7 is a diagram showing an example of an interface between a microphone and electronics device.

[0014] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

DETAILED DESCRIPTION

[0015] The present approaches allow electronic devices that use microphones to access key microphone metrics (e.g., sensitivity, low frequency roll-off (LFRO), frequency response, and phase polynomial coefficients, etc.) stored in the memories of these microphones. In other aspects, the electronic devices are able to program the microphone with specific parameters or other types of information.

[0016] In some examples, performance curves of a microphone may be modelled mathematically and stored as coefficients in the memory. For example, general linear fit, power fit, or other approaches can be used to obtain coefficients representing response curve data. Pole/Zero information with transfer function model can be used for magnitude and phase characterization. Other examples are possible.

[0017] Wider sensitivity limits (e.g., due to the user's ability to freely program the memory of the microphone) are achieved using various techniques described herein. The wider sensitivity limits, in rum, create a much higher yield when manufacturing the microphones. For example, a microphone that would have been otherwise rejected due to stringent sensitivity limit specifications may be used in end user applications because the memory of the microphone can be adjusted after manufacture. For example, after manufacture, the microphone may be communicatively coupled to a testing and/or calibrating device that can communicate with the memory of the microphone to adjust the settings or characteristics stored in the memory.

[0018] The interface between an external processor and the memory of the microphone can use any number of protocols and physical wires. For example, the I2C protocol (with dedicated registers) and SoundWire can be used. Other examples are possible.

[0019] External influences on microphone performance may be accounted for in techniques described herein. Mathematical models may describe these influences, which may be stored in the memory along with other metrics. For example, mathematical models describing the effects of temperature, humidity, and drop and aging effects (or any other suitable metric) may be stored in memory. Thus, an electronic device that uses the microphone may read these mathematical models and adjust the metrics read from memory accordingly.

[0020] For example, a mathematical model relating the effects of temperature to sensitivity metrics may be stored in the memory of a microphone. In an illustrative embodiment, the mathematical model may be stored in the memory by a manufacturer of the microphone. An external electronics device (e.g., a smartphone, a computer, a tablet, etc.) may read the sensitivity metrics and the mathematical model representing temperature effects from the microphone's memory. The customer electronics device may use the sensitivity metrics in one or more algorithms and adjust the sensitivity metrics based upon the temperature model. For instance, the mathematical model specifies sensitivity adjustments based upon temperature. The customer electronics device measures a temperature of the microphone or an ambient temperature. The customer electronics device applies the measured temperature to the mathematical model to produce an adjustment metric. An adjustment to the sensitivity metric stored in the microphone's memory can be made based on the adjustment metric. For example, the customer electronics device can read the sensitivity metric from the microphone's memory, apply the adjustment metric to the sensitivity metric to produce an adjusted sensitivity metric, and cause the adjusted sensitivity metric to be stored in the microphone's memory to be used in place of the original sensitivity metric. In an altemative embodiment, the manufacturer may communicatively couple the microphone to a testing and/or calibrating device that can communicate with the memory and the manufacturer can update or change the metrics stored in the memory of the microphone.

[0021] Referring now to FIG. 1, one example of a micro electro mechanical system (MEMS) microphone 100 is described. The microphone 100 includes a base or substrate 110, a MEMS device or transducer 102 (with diaphragm, back plate, and substrate), an integrated circuit 104, a lid or cover 106, and a port 108. The port 108 as shown here extends through the base making the microphone 100 a bottom port device. However, it will be appreciated that the port 108 may extend through the lid or cover 106 making the microphone 100 a top port device. The base 110 may be a printed circuit board in one example.

Although the microphone 100 includes a MEMS device or transducer 102, any suitable type or style of acoustic transducer may be used, such as a piezoelectric transducer. Similarly, although the embodiment of FIG. 1 includes an integrated circuit 104, any other suitable type or style of processing circuitry may be used.

[0022] The integrated circuit 104 is coupled to a first conductive pad 111 (constructed of an electrically conducting material such as a metal). The first conductive pad 111 is disposed on an interior surface of the base 110 and is coupled to a second conductive pad 112 (on the exterior surface of the base 110 and constructed of an electrically conducting material such as a metal) via a first conductive connector 114. A second conductive connector 116 couples to the second conductive pad 112 and to customer electronics device 118. Although the embodiment of FIG. 1 includes one electrical pathway (via the first conductive pad 11 1, the first conductive connector 1 14, the second conductive pad 1 12, and the second conductive connector 116) to the customer electronics device 1 18 (e.g., in addition to a ground connection), any other suitable number of electrical pathways may be used, such as to facilitate a serial communication.

[0023] The integrated circuit 104 includes or is coupled to a memory 107. In one example, the memory 107 is physically disposed within or integrated with the integrated circuit 104. In other examples, the memory 107 is a separate integrated circuit that is physically distinct from and separated from the integrated circuit 104. The memory 107 may be of any size, but in some embodiments is relatively small in memory storage size. For example, the memory 107 may be implemented as memory registers that are a few bytes (or bits) in size. Other examples are possible.

[0024] The first conductive connector 1 14 and the second conductive connector 116 may be any number of separate conductive elements such as wires, connections, or transmission lines. For instance one, two, three, etc. lines may be used. Other examples are possible.

[0025] The interface between the processor and the memory can use or conform to any number of protocols and physical wires. For example, the I2C protocol (with dedicated registers) and SoundWire protocol can be used. Other examples are possible.

[0026] In the embodiment illustrated in FIG. 1, the electronics device 118 and the microphone 100 are disposed within a device 119. For example, the electronics device 118 may be a processor and the device 1 19 may be a user device such as a laptop, smartphone, tablet, etc. In other examples, the electronics device 1 18 may include analog circuitry such as transistors, capacitors, resistors, etc.

[0027] In an illustrative embodiment, the electronics device 1 18 executes one or more algorithms that utilize information associated with the microphone 100. For example, the electronics device 118 may implement algorithms that import or utilize sensitivity and other parameters or metrics. In an illustrative embodiment, computer software that implements algorithms specific to the user device 1 19 (e.g., a cellular phone, laptop, tablet, or personal computer) utilizes the metrics. For example, noise cancellation, beamforming, and speech processing utilizes the metrics. Other examples are possible. [0028] In an illustrative embodiment, the memory 107 stores microphone metrics. The electronics device 118 reads the metrics and uses the metrics in algorithms performed by the electronics device 118. In an illustrative embodiment, the electronics device 118 reads the metrics after manufacturing has been completed and after the microphone is installed in the device 119. In an illustrative embodiment, the electronics device 118 writes metrics to the memory 107 on-the-fly after manufacturing has been complete.

[0029] In one example of the operation of the system of FIG. 1, the transducer 102 converts sound energy into electrical signals and sends the electrical signals to the integrated circuit 104 for processing. The memory 107 is configured to store at least one microphone characterization metric. The integrated circuit 104 can use the metrics stored in the memory 107 while processing the electrical signal from the transducer 102. For example, the stored metric may be a sensitivity metric and the integrated circuit 104 can increase or decrease the sensitivity of the microphone 100 based on the stored metric.

[0030] In an illustrative embodiment, the electronics device 118 reads the microphone characterization metric from the memory 107. In an illustrative embodiment, the electronics device 118 writes the microphone characterization metric to the memory 107. The microphone characterization metric may be, but is not limited to, a microphone sensitivity, a low frequency roll-off, a frequency response, a phase response (e.g., within a bandwidth of interest), poles, zeroes, resonances, Q factors of resonances, acoustic overload point (AOP) limits, and/or a microphone total harmonic distortion (THD). In an illustrative embodiment, a frequency response stored in the microphone includes one or more of a low frequency roll- off, a frequency response over a bandwidth, a phase response over a bandwidth, a resonance, and a total harmonic distortion. The metrics may be combinations of these elements. Other examples are possible. In some embodiments, by storing such parameters in the memory 107, such parameters need not be stored in non-volatile memory of the microphone. For example, in some embodiments, the memory 107 may be a one-time programmable (OTP) memory, a multiple-times programmable (MTP) memory (e.g., programmable a limited number of times, such as five times), or a flash memory. In some such embodiments, the memory 107 can be programmed (e.g., during manufacture, at a testing facility, etc.) to include the microphone characterization metric(s), and at least some of the metrics may not be required to be stored in non-volatile memory. Thus, the amount of non-volatile memory in the microphone can be reduced. [0031] The memory 107 may be a volatile memory (e.g., a random-access memory (RAM)). In other examples, the memory 107 is a non-volatile memory (e.g., a read-only memory (ROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), etc.). Other examples are possible.

[0032] In some examples, the microphone characterization metric is a code. The code may be converted to a plurality of characterization parameters using a lookup table. In other examples, the microphone characterization metric are coefficients, and the coefficients are used algorithmically to reconstruct parameters or response curves. In still other examples, a data compression method (e.g., lossless or lossy) along with a cycle redundancy check (CRC) algorithm is performed on the at least one microphone characterization metric before the at least one microphone characterization metric is initially stored in memory to reduce the size of the at least one microphone characterization metric.

[0033] Referring now to FIG. 2, one example of an integrated circuit 200 is described. The integrated circuit 200 may be an application specific integrated circuit (ASIC) that is disposed in a microphone. The integrated circuit 200 includes analog electronics 202, a logic and processing module 204, and a memory 206. In alternative embodiments, additional, fewer, and/or different elements may be used.

[0034] In an illustrative embodiment, the analog electronics 202 receives an electrical signal from a transducer (e.g., the transducer 102) and converts and/or processes the signal. For example, the analog electronics may perform noise removal functions and/or convert the signal received from the transducer from one format to another format (e.g., from analog to digital). In an illustrative embodiment, the logic and processing module 204 controls the operation of the analog electronics 202.

[0035] The memory 206 may be a volatile memory (e.g., a random-access memory (RAM)). In other examples, the memory 206 is a non-volatile memory (e.g., a read-only memory (ROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), etc.). Other examples are possible.

[0036] The memory 206 stores microphone characterization metrics. The microphone characterization metric may be, but is not limited to, a microphone sensitivity, a low frequency roll-off, a frequency and/or phase response (e.g., within a bandwidth of interest), and/or a microphone THD. The metrics may be combinations of these elements. Other examples are possible. An electronics device (e.g., the electronics device 118 of FIG. 1) may read and/or write these metrics to the memory 206.

[0037] The memory 206 is shown in FIG. 2 as being physically incorporated into or with the integrated circuit 200. In alternative embodiments, the memory 206 may be implemented as a separated integrated circuit.

[0038] Referring now to FIG. 3, one example of an approach for reading and writing data from an electronics device to a memory in a microphone is described. The example of FIG. 3 can be implemented with any number of physical wires (e.g., 1, 2, 4, etc.) between the memory and the external consumer electronics device. The read and write signals can follow any suitable type of format.

[0039] At step 302, a read signal is sent from the consumer electronics device to the integrated circuit. The read signal may include an address of the memory location that is desired to be accessed. At step 304, the read signal is received, and the memory at the integrated circuit is accessed (e.g., the memory location indicated by the address is accessed). At step 306, data is returned from the integrated circuit to the consumer electronics device. For example, the data from the desired memory location is transmitted to the consumer electronics device. Together, steps 302, 304, and 306 are a read operation from the perspective of the consumer electronics device.

[0040] Next, a write operation can be made. At step 308, a write signal is sent from the consumer electronics device to the integrated circuit. The write signal may indicate an address of a memory in the integrated circuit to which data is to be written. At step 310, the data to be written to the memory in the integrated circuit is transmitted from the consumer electronics device to the integrated circuit. The data is stored in the memory of the integrated circuit (e.g., at the address indicated in the write signal).

[0041] Referring now to FIG. 4, one example of using codes to minimize the size of data stored in the memory of the integrated circuit is described. In this example, the microphone memory does not store raw, unaltered data. Rather, the memory stores codes. Each code 402 represents one or more microphone characterization metrics. For example, the code 402 may represent a sensitivity pattern or parameter set. The code 402 is read out of the memory of the integrated circuit by the consumer electronics device. The consumer electronics device can access a look-up table 404.

[0042] In example illustrated in FIG. 4, the code 402 is two bits and can assume four Boolean values: 00, 01, 10, and 11. The four values are indicated in rows 406, 408, 410, and 412. Each code corresponds to the parameter set indicated in its row. For example, code 00 corresponds to parameter set 1. Code 01 corresponds to parameter set 2. Code 10 corresponds to parameter set 3. Code 11 corresponds to parameter set 4. Each parameter set may include parameters and performance curves related to sensitivity, low frequency roll-off (LFRO), frequency response, and/or phase polynomial coefficients, or any other suitable metric.

[0043] The consumer electronics device effectively can convert the code into a parameter set that is stored at the consumer electronics device. Thus, the memory in the integrated circuit at the microphone does not have to store the full parameter set. In this example, the memory need only have two bits. Consequently, the memory at the integrated circuit can be a very small memory and need not take up a great deal of space, thereby realizing space savings at the microphone. Although the example illustrated in FIG. 4 allows four parameter sets to be used, additional bits in the code allows additional parameter sets to be used.

[0044] Referring now to FIG. 5, 6, and 7, an interface between a microphone memory and an integrated circuit is described. The integrated circuit includes a memory that can communicate with the consumer electronics device with several physical layer approaches including, but not limited to, 4-Wire (FIG. 5), 2-Wire (FIG. 6), and 1-Wire (FIG. 7) approaches. In some embodiments, the microphone may additionally or alternatively communicate with devices other than a consumer electronics device, such as a testing and/or calibrating electronics device of a manufacturer of the microphone that stores updated characteristics in the integrated circuit (e.g., during a manufacturing or testing phase).

[0045] In the example of FIG. 5, four lines couple the memory to the consumer electronics device and include a Memory Block Processor DATA (Write) line 502, a DATA (Read) line 504, an Integrated Circuit Consumer Electronics Device CLOCK line 506, and a SELECT line 508. SPI-compliant protocols may use this approach. In an illustrative embodiment, each line represents a conductive pathway between the consumer electronics device and the microphone memory. In operation, the consumer electronics device sends a write request on DATA (Write) line 502 at a rate controlled by the CLOCK line 506 that is enabled when the SELECT line 508 has been properly asserted to include a specified memory address contained in the integrated circuit memory. In a read operation, the consumer electronics device sends a read request on DATA (read) line 504 at a rate controlled by the CLOCK line 506 that is enabled when the SELECT line 508 has been properly asserted to include a specified memory address contained in the integrated circuit memory. For a write operation, the consumer electronics device writes metric data to the memory on DATA (Write) line 502. For a read operation, the consumer electronics device proceeds to read the metric data from memory on DATA (Read) line 504. Data metrics read from integrated circuit memory can be processed in the consumer electronics device to be implemented in algorithms. For example, such algorithms may determine adjusted parameters to store in the microphone memory. In another example, the algorithms may incorporate the parameters in additional processing of the audio signal transmitted from the microphone.

[0046] Referring now to FIG. 6, a two wire example is shown. The consumer electronics device sends a read/write request on a DATA (Write/Read) line 602 at a rate controlled by a CLOCK line 604 to a specified memory address contained in integrated circuit memory. For example, the I2C and SoundWire protocols conform to the interface of FIG. 6. In the case of the read by the consumer electronics device, the data (e.g., microphone characterization metrics) is transmitted from the microphone memory to the consumer electronics device over line 602. In the case of a write, data (e.g., updated microphone characterization metrics) is transmitted from the consumer electronics device to the memory over line 602. In the example of FIG. 6, the consumer electronics device may receive an acknowledgment that data has been written to memory or read from the microphone memory over the line 602. Data metrics read from integrated circuit memory may be processed in consumer electronics device to be implemented in algorithms.

[0047] Referring now to FIG. 7, a one wire example is described. In this example, a single wire 702 is used for communications between the consumer electronics device and the memory of the integrated circuit. The consumer electronics device sends a read/write request on the DATA (Write/Read) line 702 to a specified memory address contained in the integrated circuit memory. The request is followed by the data. In the case of the read command, the data is transmitted from the memory to the consumer electronics device over the line 702. In the case of a write command, the data is transmitted from the consumer electronics device to the memory over the line 702. In some aspects, the consumer electronics device receives acknowledgment that data has been written to memory or read from memory in the integrated circuit. Data metrics read from integrated circuit memory are processed in consumer electronics device to be implemented to end user algorithms.

[0048] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A method in a microphone assembly including a MEMS transducer and processing circuitry disposed in a housing formed by a cover and a base with a conductive pad, the processing circuitry including memory storing microphone characterization information, the method comprising:

receiving, via the conductive pad of the microphone assembly, a request for the microphone characterization information stored in the memory;

transmitting, from the microphone assembly, the microphone characterization information via the conductive pad in response to the request,

wherein the microphone characterization information is indicative of a frequency response characteristic of the microphone assembly.

2. The method of Claim 1, wherein the frequency response characteristic is a low frequency roll-off of the microphone assembly.

3. The method of Claim 2, wherein the frequency response characteristic is a frequency response over a bandwidth of the microphone assembly.

4. The method of Claim 1, wherein the frequency response characteristic is a phase response over a bandwidth of the microphone assembly

5. The method of Claim 1, wherein the frequency response characteristic includes a model of the frequency response characteristic of the microphone assembly.

6. The method of Claim 5, wherein the frequency response characteristic includes at least one of pole, zero, resonance, or total harmonic distortion of the microphone assembly.

7. The method of Claim 1, wherein the frequency response characteristic includes at least one of a low frequency roll-off, a frequency response over a bandwidth, or a phase response over the bandwidth of the microphone assembly.

8. The method of Claim 1, wherein the frequency response characteristic includes a total harmonic distortion of the microphone assembly.

9. A microphone assembly comprising:

a housing formed by a cover and a substrate including a conductive pad, the housing including a sound port;

a transducer disposed in the housing and configured to convert acoustic energy entering the housing via the sound port into an electrical signal;

an electrical circuit disposed in the housing and electrically coupled to the transducer and to the conductive pad, the electrical circuit including memory storing microphone characterization information,

wherein the electrical circuit is configured to:

process electrical signals received from the transducer;

receive, via the conductive pad, a request for the microphone characterization information stored in memory; and

transmit, via the conductive pad, the microphone characterization information stored in memory in response to the request,

wherein the microphone characterization information stored in memory is indicative of a frequency response characteristic of the microphone assembly.

10. The microphone assembly of Claim 9, wherein the frequency response characteristic includes a low frequency roll-off of the microphone assembly.

11. The microphone assembly of Claim 9, wherein the frequency response characteristic includes a frequency response of the microphone assembly over a bandwidth.

12. The microphone assembly of Claim 9, wherein the frequency response characteristic is a phase response of the microphone assembly over a bandwidth.

13. The microphone assembly of Claim 9, wherein the frequency response characteristic includes a total harmonic distortion of the microphone assembly.

14. The microphone assembly of Claim 9, wherein the microphone

characterization information includes pole, zero, or resonance information for the frequency response characteristic of the microphone assembly.

15. The microphone assembly of Claim 9, wherein the microphone

characterization information stored in memory is embodied as a code useable to obtain the frequency response characteristic of the microphone assembly using a look-up table.

16. The microphone assembly of Claim 9, wherein the microphone

characterization information stored in memory is embodied as one or more coefficients usable to reconstruct the frequency response characteristic of the microphone assembly.

17. The microphone assembly of Claim 9, wherein the microphone

characterization information stored in memory is embodied as compressed data.

18. An acoustic signal processing circuit configured to be electrically coupled to a transducer and a conductive pad of a microphone assembly, the acoustic signal processing circuit comprising:

a memory configured to store microphone characterization information;

an input configured to receive a request for the microphone characterization information from the conductive pad;

an output; and

processing circuitry configured to:

process electrical signals received from the transducer;

receive the request via the input;

retrieve, from the memory, the microphone characterization information; and transmit, via the output, the microphone characterization information to the conductive pad in response to the request;

19. The acoustic signal processing circuit of Claim 18, wherein the frequency response characteristic is selected from a group comprising low frequency roll-off, frequency response over a bandwidth, phase response over a bandwidth, resonance, and total harmonic distortion.

20. The acoustic signal processing circuit of Claim 18, wherein the microphone characterization information is a model of the frequency response characteristic of the microphone assembly.