Abstract:
A microphone includes a base; a micro electro mechanical system (MEMS) device disposed on the base, the MEMS device configured to convert sound into a first electrical signal; an integrated circuit disposed on the base and coupled to the MEMS device; a photo diode disposed on the base, the photo diode configured to convert light into a second electrical signal. At least one of the first electrical signal and the second electrical signal is processed by the integrated circuit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This patent claims benefit under 35 U.S.C. §119(e) to U.S. Provisional Application No. 62/084,369 entitled “Photosensitive microphone” filed Nov. 25, 2014, the content of which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    This application relates to microphones and, more specifically, to microphones providing photosensitive functionality. 
       BACKGROUND OF THE INVENTION 
       [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, a MEMS die includes a diagram and a 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 consumer electronic devices such as personal computers or cellular phones. 
         [0004]    Photo sensors are also used in many consumer electronic devices as discrete components that are separate from the acoustic elements such as the microphones. However, these photosensitive elements require a large footprint and this is visible to the consumer. In many cases, the sensors appear large and unsightly on the exterior of the device (e.g., on the exterior of the cellular phone). This negative cosmetic appearance is a negative influence on consumers who may not wish to purchase the device because of the unsightly appearance. 
         [0005]    These problems of previous approaches have resulted in some user dissatisfaction with these 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 wherein: 
           [0007]      FIG. 1A  comprises a side cutaway view of a top port microphone according to various embodiments of the present invention; 
           [0008]      FIG. 1B  comprises a side cutaway view of a top port microphone according to various embodiments of the present invention; 
           [0009]      FIG. 1C  comprises a side cutaway view of a MEMS on lid or bottom port microphone according to various embodiments of the present invention; 
           [0010]      FIG. 1D  comprises a side cutaway view of a MEMS on lid or bottom port microphone according to various embodiments of the present invention; 
           [0011]      FIG. 1E  comprises a side cutaway view of a MEMS on lid or bottom port microphone according to various embodiments of the present invention; 
           [0012]      FIG. 1F  comprises a side cutaway view of a MEMS on lid or bottom port microphone according to various embodiments of the present invention; 
           [0013]      FIG. 1G  comprises a side cutaway view of a MEMS on lid or bottom port microphone according to various embodiments of the present invention; 
           [0014]      FIG. 2A  comprises a block diagram of a MEMS microphone according to various embodiments of the present invention; 
           [0015]      FIG. 2B  comprises a block diagram of a MEMS microphone according to various embodiments of the present invention; 
           [0016]      FIG. 2C  comprises a block diagram of a MEMS microphone according to various embodiments of the present invention; 
           [0017]      FIG. 2D  comprises a block diagram of a MEMS microphone according to various embodiments of the present invention; 
           [0018]      FIG. 3A  comprises a block diagram of a MEMS microphone according to various embodiments of the present invention; 
           [0019]      FIG. 3B  comprises a block diagram of a MEMS microphone according to various embodiments of the present invention. 
       
    
    
       [0020]    Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. 
       DETAILED DESCRIPTION 
       [0021]    The present approaches provide photo diodes or other photo sensing devices within MEMS microphone assemblies. The approaches described herein are cost effective to implement and result in a pleasing visual appearance for the consumer device (in which the MEMS microphone is disposed) because the photo diode does not add any additional visual footprint compared to what the consumer device would already need for the microphone alone. 
         [0022]    Referring now to  FIGS. 1A-1G  various examples of microphones/microphone assemblies are described. Each of these figures utilizes similarly numbered elements. 
         [0023]    Referring now to  FIG. 1A , one example of a microphone  100  is described. The microphone  100  includes a MEMS device  102 , an application specific integrated circuit (ASIC)  104 , and a photo diode  106 . The MEMS device  102  converts sound energy into a first electrical signal and, in one aspect, includes a diaphragm and a back plate. The ASIC  104  receives the first electric signal from the MEMS device  102  and performs further processing (e.g., amplification and/or noise removal to mention two examples) on the first electrical signal. The photo diode  106  receives light energy and converts this light energy into a second electrical signal. The second electrical signal may be further processed by the ASIC  104 . As used herein, a photo diode is any photo-sensitive device that receives light energy and converts the light energy into electrical signals. 
         [0024]    The microphone  100  in  FIG. 1A  also includes a cover  112 , and the MEMS device  102 , the ASIC  104  and the photo diode  106  are disposed on a base  110 . The base  110  may be a printed circuit board, in one example. The cover  112  is coupled to the base  110  to enclose the MEMS device  102 , the ASIC  104 , and the photo diode  106 . A port  114  extends through the cover  112  making the microphone  100  of  FIG. 1A  a top port device. An encapsulation  122  extends about the ASIC  104 . The encapsulation  122  may be a silicon polymerin one example, and is used to protect the ASIC  104 . Both light and sound energy enter the microphone via the port  114 . 
         [0025]    Referring now to  FIG. 1B , another example of a microphone  100  is described. The microphone  100  includes a MEMS device  102 , an application specific integrated circuit (ASIC)  104 , and a photo diode  106 . The MEMS device  102  converts sound energy into a first electrical signal and, in one aspect, includes a diaphragm and a back plate. The ASIC  104  receives the first electric signal from the MEMS device  102  and performs further processing (e.g., amplification and/or noise removal to mention two examples) on the first electrical signal. The photo diode  106  receives light energy and converts this light energy into a second electrical signal. The second electrical signal may be further processed by the ASIC  104 . 
         [0026]    The microphone  100  in  FIG. 1B  also includes a cover  112 , and the MEMS device  102 , the ASIC  104  and the photo diode  106  are disposed on a base  110 . The base  110  may be a printed circuit board, in one example. The cover  112  is coupled to the base  110  to enclose the MEMS device  102 , the ASIC  104 , and the photo diode  106 . A port  114  extends through the cover  112  making the microphone  100  of  FIG. 1B  a top port device. The photo diode  106  may be coupled to or incorporated into the ASIC  104  in this example. Both light and sound energy enter the microphone via the port  114 . 
         [0027]    Referring now to  FIG. 1C , another example of a microphone  100  is described. The microphone  100  includes a MEMS device  102 , an application specific integrated circuit (ASIC)  104 , and a photo diode  106 . The MEMS device  102  converts sound energy into a first electrical signal and, in one aspect, includes a diaphragm and a back plate. The ASIC  104  receives the first electric signal from the MEMS device  102  and performs further processing (e.g., amplification and/or noise removal to mention two examples) on the first electrical signal. The photo diode  106  receives light energy and converts this light energy into a second electrical signal. The second electrical signal may be further processed by the ASIC  104 . 
         [0028]    The microphone  100  in  FIG. 1C  also includes a lid  112 , side walls  111 , and the MEMS device  102 , the ASIC  104  and the photo diode  106  are disposed on the lid  112 . A base  110  is coupled to the side walls  111 . The base  110  may be a printed circuit board, in one example. The lid  112  encloses the MEMS device  102 , the ASIC  104 , and the photo diode  106 . A first port  114  extends through the lid  112  and communicates with the MEMS device  102 . A second port  115  extends through the lid  112  and communicates with the photo diode  106 . The second port  115  may be filled with an epoxy (or similar material) in order to filter light wavelengths and/or protect the photodiode from environmental conditions. The photo diode  106  may be coupled to the side of the ASIC  104  in this example. An encapsulation  122  extends about the ASIC  104  and the photo diode  106 . The encapsulation  122  may be a silicon polymer in one example, and is used to protect the ASIC  104 . The microphone  100  of  FIG. 1C  may be classified as a MEMS-on-lid device, or as a bottom port device. The port  114  allows sound to enter the microphone while the port  115  allows light to enter the microphone. 
         [0029]    Referring now to  FIG. 1D , another example of a microphone  100  is described. The microphone  100  includes a MEMS device  102 , an application specific integrated circuit (ASIC)  104 , and a photo diode  106 . The MEMS device  102  converts sound energy into a first electrical signal and, in one aspect, includes a diaphragm and a back plate. The ASIC  104  receives the first electric signal from the MEMS device  102  and performs further processing (e.g., amplification and/or noise removal to mention two examples) on the first electrical signal. The photo diode  106  receives light energy and converts this light energy into a second electrical signal. The second electrical signal may be further processed by the ASIC  104 . 
         [0030]    The microphone  100  in  FIG. 1D  also includes a lid  112 , side walls  111 , and the MEMS device  102 , the ASIC  104  and the photo diode  106  are disposed on the lid  112 . A base  110  is coupled to the side walls  111 . The base  110  may be a printed circuit board, in one example. The lid  112  encloses the MEMS device  102 , the ASIC  104 , and the photo diode  106 . A first port  114  extends through the lid  112  and communicates with the MEMS device  102 . A second port  115  extends through the lid  112  and communicates with the photo diode  106 . The second port  115  may be filled with an epoxy (or similar material) in order to filter light wavelengths and/or protect the photodiode from environmental conditions. The photo diode  106  incorporated into or be held by the ASIC  104  in this example. An encapsulation  122  extends about the ASIC  104  and the photo diode  106 . The encapsulation  122  may be a silicon polymer, in one example, and is used to protect the ASIC  104 . The microphone  100  of  FIG. 1D  may be classified as a MEMS-on-lid device, or as a bottom port device. The port  114  allows sound to enter the microphone while the port  115  allows light to enter the microphone. 
         [0031]    Referring now to  FIG. 1E , another example of a microphone  100  is described. The microphone  100  includes a MEMS device  102 , an application specific integrated circuit (ASIC)  104 , and a photo diode  106 . The MEMS device  102  converts sound energy into a first electrical signal and, in one aspect, includes a diaphragm and a back plate. The ASIC  104  receives the first electric signal from the MEMS device  102  and performs further processing (e.g., amplification and/or noise removal to mention two examples) on the first electrical signal. The photo diode  106  receives light energy and converts this light energy into a second electrical signal. The second electrical signal may be further processed by the ASIC  104 . 
         [0032]    The microphone  100  in  FIG. 1E  includes a lid  112 , side walls  111 , and the MEMS device  102 , the ASIC  104  and the photo diode  106  are disposed on the lid  112 . A base  110  is coupled to the side walls  111 . The base  110  may be a printed circuit board, in one example. The lid  112  encloses the MEMS device  102 , the ASIC  104 , and the photo diode  106 . A first port  114  extends through the lid  112  and communicates with the MEMS device  102 . A second port  115  extends through the lid  112  and communicates with the photo diode  106 . The second port  115  may be filled with an epoxy (or similar material) in order to filter light wavelengths and/or protect the photodiode from environmental conditions. The photo diode  106  is separate from the ASIC  104  in this example. An encapsulation  122  extends about the ASIC  104 . The encapsulation  122  may be a silicon polymer in one example, and is used to protect the ASIC  104 . The microphone  100  of  FIG. 1E  may be classified as a MEMS-on-lid device, or as a bottom port device. The port  114  allows sound to enter the microphone while the port  115  allows light to enter the microphone. 
         [0033]    Referring now to  FIG. 1F , another example of a microphone  100  is described. The microphone  100  includes a MEMS device  102 , an application specific integrated circuit (ASIC)  104 , and a photo diode  106 . The MEMS device  102  converts sound energy into a first electrical signal and, in one aspect, includes a diaphragm and a back plate. The ASIC  104  receives the first electric signal from the MEMS device  102  and performs further processing (e.g., amplification and/or noise removal to mention two examples) on the first electrical signal. The photo diode  106  receives light energy and converts this light energy into a second electrical signal. The second electrical signal may be further processed by the ASIC  104 . 
         [0034]    The microphone  100  in  FIG. 1F  includes a lid  112 , side walls  111 , and the MEMS device  102 , the ASIC  104  and the photo diode  106  are disposed on the lid  112 . A base  110  is coupled to the side walls  111 . The base  110  may be a printed circuit board, in one example. The lid  112  encloses the MEMS device  102 , the ASIC  104 , and the photo diode  106 . A port  114  extends through the lid  112  and communicates with the MEMS device  102  and the photo diode  106 . The photo diode  106  is incorporated into the MEMS device in this example. An encapsulation  122  extends about the ASIC  104  and the photo diode  106 . The encapsulation  122  may be a silicon polymer in one example, and is used to protect the ASIC  104 . The microphone  100  of  FIG. 1E  may be classified as a MEMS-on-lid device, or as a bottom port device. Both light and sound energy enter the microphone via the port  114 . 
         [0035]    Referring now to  FIG. 1G , another example of a microphone  100  is described. The microphone  100  includes a MEMS device  102 , an application specific integrated circuit (ASIC)  104 , and a photo diode  106 . The MEMS device  102  converts sound energy into a first electrical signal and, in one aspect, includes a diaphragm and a back plate. The ASIC  104  receives the first electric signal from the MEMS device  102  and performs further processing (e.g., amplification and/or noise removal to mention two examples) on the first electrical signal. The photo diode  106  receives light energy and converts this light energy into a second electrical signal. The second electrical signal may be further processed by the ASIC  104 . 
         [0036]    The microphone  100  in  FIG. 1G  also includes a lid  112 , side walls  111 , and the MEMS device  102 , the ASIC  104  and the photo diode  106  are disposed on the lid  112 . A base  110  is coupled to the side walls  111 . The base  110  may be a printed circuit board, in one example. The lid  112  encloses the MEMS device  102 , the ASIC  104 , and the photo diode  106 . A port  114  extends through the lid  112  and communicates with the MEMS device  102  and with the photo diode  106 . The photo diode  106  incorporated into or be held by the ASIC  104  in this example. An encapsulation  122  extends about the ASIC  104  and the photo diode  106 . The encapsulation  122  may be a silicon polymer, in one example, and is used to protect the ASIC  104 . The microphone  100  of  FIG. 1G  may be classified as a MEMS-on-lid device, or as a bottom port device. The port  114  allows sound to enter the microphone while the port  115  allows light to enter the microphone. 
         [0037]    In the examples of  FIGS. 1C-1G , the walls  111  and lid  112  could be replaced with a single metal can. 
         [0038]    In any of the examples of  FIGS. 1A-1G , sound energy is received and converted into electrical signals by the MEMS device  102 . The photo diode  106  is any photo-sensitive device that receives light energy and converts the light energy into electrical signals. As mentioned above, in some arrangements the light and sound enter through the same port, while in other arrangements light and sound enter through different ports. Light may also enter through semi-translucent or completely translucent embodiments of the MEMS microphone package. The electrical signals received from the MEMS device  102  and the photo diode  106  may be further processed by the ASIC  104 . After processing, the processed signals can be sent to a consumer electronics device, for instance, via pads (not shown) on the base  110  that are coupled to the ASIC  104 . 
         [0039]    Referring now to  FIGS. 2A-2D  various examples of microphones are described. Each of these figures utilizes similarly numbered elements. 
         [0040]    Referring now to  FIG. 2A , another example of a microphone  200  is described. The microphone  200  includes a charge pump  202 , a MEMS device  204 , an ASIC  206  and a photo diode  208 . The ASIC  206  includes a first amplifier  220 , a first analog-to-digital converter (ADC)  222 , a second ADC  224 , and a second amplifier  226 . The first ADC  222  and second ADC are coupled to a Flexlink-compliant data bus  228 , which transmits the pulse code modulation (PCM) data that it receives. 
         [0041]    In operation, the charge pump  202  provides voltage to the MEMS device  204 , which receives sound energy and transforms the sound energy to an electrical signal that is received by the ASIC  206 . The signal is buffered and amplified by the first amplifier  220  and converted into a digital PCM signal by the first ADC  222  and placed on the bus  228 . The photo diode  208  receives light energy, converts this to an electric signal that is received by the second amplifier  226 , which buffers and amplifies this analog signal. The analog signal is transformed into a PCM digital signal by the second ADC  224 , which places the digital signal on the bus  228 . 
         [0042]    Referring now to  FIG. 2B , another example of a microphone  200  is described. The microphone  200  includes a charge pump  202 , a MEMS device  204 , an ASIC  206  and a photo diode  208 . The ASIC  206  includes a first amplifier  220 , a first sigma delta converter  222 , a second sigma delta converter  224 , and a second amplifier  226 . The first sigma delta converter  222  and the second sigma delta converter  224  are coupled to a multiplexer  230 , which chooses which input signal to place on output data line  228 . The designation of each signal on the left or right channel is predefined by design. 
         [0043]    In operation, the charge pump  202  provides voltage to the MEMS device  204 , which receives sound energy and transforms the sound energy to an electrical signal that is received by the ASIC  206 . The signal is buffered and amplified by the first amplifier  220  and converted into a digital PDM signal by the sigma delta converter  222 . The photo diode  208  receives light energy, converts this to an analog electric signal that is received by the second amplifier  226  which buffers and amplifies this analog signal. The analog signal is transformed into a PDM digital signal by the second sigma delta converter  224 . The multiplexer  230  chooses which of the input signals to place on output data line  228 . 
         [0044]    Referring now to  FIG. 2C , another example of a microphone  200  is described. The microphone  200  includes a charge pump  202 , a MEMS device  204 , an ASIC  206 , a photo diode  208 , a first analog to digital converter  210 , and an I2C interface  212  The ASIC  206  includes an amplifier  220 , and a second analog-to-digital converter (ADC)  222  that are coupled to a Flexlink-compliant data bus  228 . 
         [0045]    In operation, the charge pump  202  provides voltage to the MEMS device  204 , which receives sound energy and transforms the sound energy to an electrical signal that is received by the ASIC  206 . The signal is buffered and amplified by the amplifier  220  and converted into a digital PCM signal by the ADC  222 . The ADC  222  places the data on the data bus  228 . 
         [0046]    The photo diode  208  receives light energy, converts this to an analog electric signal that is received by the first ADC  210 , which converts this into a digital signal compatible with the I2C interface  212 , which places the signal onto I2C line  230 . 
         [0047]    Referring now to  FIG. 2D , another example of a microphone  200  is described. The microphone  200  includes a charge pump  202 , a MEMS device  204 , an ASIC  206 , a photo diode  208 , a first analog to digital converter  210 , and an I2C interface  212 . The ASIC  206  includes an amplifier  220 , a sigma delta converter  222  that is coupled to a data bus  228 . 
         [0048]    In operation, the charge pump  202  provides voltage to the MEMS device  204 , which receives sound energy and transforms the sound energy to an electrical signal that is received by the ASIC  206 . The signal is buffered and amplified by the amplifier  220  and converted into a digital PDM signal by the sigma delta converter  222 . The sigma delta converter  222  places the data on the data bus  228 . 
         [0049]    The photo diode  208  receives light energy, converts this to an analog electric signal that is received by the first ADC  210 , which converts this into a digital signal compatible with the I2C interface  212 , which places the signal onto I2C line  230 . 
         [0050]    In any of the embodiments described in  FIGS. 2A-2D , a single analog to digital converter may be used instead of two discrete converters. The analog output of the light-sensitive element can also be transmitted without being converted to a digital signal in any of these embodiments. 
         [0051]    Referring now to  FIG. 3A , an example of a microphone  300  is described. The microphone  300  includes a charge pump  302 , a MEMS device  304 , an ASIC  306 , a photo diode  308 . The ASIC  306  includes an amplifier  320 , an analog-to-digital converter (ADC)  322  that is coupled to a data bus  328 . 
         [0052]    In operation, the charge pump  302  provides voltage to the MEMS device  304 , which receives sound energy and transforms the sound energy to an electrical signal that is received by the ASIC  306 . The signal is buffered and amplified by the amplifier  320  and converted into a digital PDM signal by the ADC  322 . The ADC  322  places the data on the data bus  328 . The photo diode  308  receives light energy, converts this to an analog electric signal that is transmitted outside the microphone  300  (e.g., to an external ADC or processor). 
         [0053]    Referring now to  FIG. 3B , an example of a microphone  300  is described. The microphone  300  includes a charge pump  302 , a MEMS device  304 , an ASIC  306 , a photo diode  308 . The ASIC  306  includes an amplifier  320  that is coupled to an analog output  330 . 
         [0054]    In operation, the charge pump  302  provides voltage to the MEMS device  304 , which receives sound energy and transforms the sound energy to an electrical signal that is received by the ASIC  306 . The signal is buffered and amplified by the amplifier  320  and placed the data on the analog output  330 . The photo diode  308  receives light energy, converts this to an analog electric signal that is transmitted outside the microphone  300  (e.g., to an external ADC or processor). 
         [0055]    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.