Temperature compensated microphone
View Patent ↗A method and a device for eliminating or minimizing the sensitivity changes in a microphone due to temperature changes. The temperature-induced changes in the sensitivity can be caused by the changes in the sound-to-electrical signal transducer, in the microphone membrane, in the ASIC or other reasons. One or more temperature dependent components in the microphone or in a microphone module are used to offset the temperature-induced changes in the sensitivity. Sensitivity of a microphone is defined as the output voltage for a specific acoustic stimulus and load condition.
1. An apparatus, comprising:
a micro-electro-mechanical system microphone, comprising:
a micro-electro-mechanical system microphone element comprising a sound-to-electrical signal converter, the converter configured to provide an electrical signal to an input of at least one amplifier module in response to a sound signal; and
an integrated circuit comprising:
the at least one amplifier module configured to respond to the electrical signal for providing an amplified signal so as to provide an electrical output based on a sensitivity value defined by a relationship between the sound signal and the electrical output; and
a temperature dependent element configured to provide a change signal indicative of a change in temperature, the change signal arranged to change a gain of the at least one amplifier for maintaining the sensitivity value substantially constant in a temperature range.
2. An apparatus according to claim 1 , wherein the at least one amplifier module comprises a pre-amplification module configured to respond to the electrical signal for providing a pre-amplified signal, and a second amplification module configured to respond to the pre-amplified signal for providing the electrical output, and wherein the change signal comprises a voltage for controlling a pre-amplification gain in the pre-amplification module.
3. An apparatus according to claim 1 , wherein the at least one amplifier module comprises a pre-amplification module configured to respond to the electrical signal for providing a pre-amplified signal, and a second amplification module configured to respond to the pre-amplified signal for providing the electrical output, wherein the temperature dependent element is a part of the pre-amplification module for providing a voltage for controlling a pre-amplification gain in the pre-amplification module.
4. A method comprising:
providing, in a micro-electro-mechanical system microphone, a micro-electro-mechanical system microphone element comprising a sound-to-electrical signal converter, the converter configured to provide an electrical signal to an input of at least one amplifier in response to a sound signal;
arranging, in an integrated circuit in the micro-electro-mechanical system microphone, a temperature dependent element for providing a change signal for use in the at least one amplifier, the at least one amplifier being part of the integrated Circuit and configured to provide an electrical output based on a sensitivity value defined by a relationship between the sound signal and the electrical output, the change signal indicative of a change in temperature, the micro-electro-mechanical system microphone configured to respond to the sound signal for providing the electrical output based on a sensitivity value of the micro-electro-mechanical system microphone; and
maintaining, in the micro-electro-mechanical system microphone and by using at least the at least one amplifier, the sensitivity value of the micro-electro-mechanical system microphone substantially constant in a temperature range based on the change signal.
5. A method according to claim 4 , further comprising conveying the change signal to the amplifier for adjusting gain so as to maintain the sensitivity value substantially constant.
6. A method according to claim 4 , wherein the at least one amplifier comprises a pre-amplification module and a second amplification module, and wherein the method further comprises: pre-amplifying using the pre-amplification module the electrical signal for providing a pre-amplified signal; and further amplifying by the second amplification module the pre-amplified signal for providing the electrical output, wherein said pre-amplifying is adjusted based on the change signal so as to maintain the sensitivity value substantially constant.
7. A method according to claim 6 , wherein the change signal is provided in a voltage for adjusting said pre-amplifying.
8. An electronic device, comprising:
first and second micro-electro-mechanical system microphones, each of the first and second micro-electro-mechanical system microphones comprising:
a micro-electro-mechanical system microphone element comprising a sound-to-electrical signal converter, the converter configured to receive a sound signal and provide an electrical signal indicative of the sound signal; and
an amplification part, responsive to the electrical signal, for providing an electrical output of the micro-electro-mechanical system microphone based on a sensitivity value defining a relationship between the sound signal and the electrical output, the amplification part having a gain arranged to respond to a change in temperature for maintaining the sensitivity value substantially constant in a temperature range;
and
a control module configured to equalize the sensitivity value of the first microphone to the sensitivity value of the second microphone.
9. An electronic device according to claim 8 , wherein each of the first and second micro-electro-mechanical system microphones further comprises: a temperature dependent element for providing a change signal indicative of the change in temperature, the change signal arranged to change the gain of the amplification part for maintaining the sensitivity value of the micro-electro-mechanical system microphone substantially constant in a temperature range based on the change signal.
10. An electronic device according to claim 9 , wherein the amplification part for each of the first and second micro-electro-mechanical system microphones comprises: a pre-amplification module configured to respond to the electrical signal for providing a pre-amplified signal, and a second amplification module configured to the pre-amplified signal for providing the electrical output, and wherein the change signal comprises a voltage for controlling a pre-amplification gain in the pre-amplification module.
11. An electronic device according to claim 9 , wherein the amplification part for each of the first and second micro-electro-mechanical system microphones comprises a pre-amplification module configured to respond to the electrical signal for providing a pre-amplified signal, and a second amplification module configured to respond to the pre-amplified signal for providing the electrical output, wherein the pre-amplification module comprises the temperature dependent element providing a voltage indicative of the change signal for controlling a pre-amplification gain in the pre-amplification module.
12. An electronic device according to claim 8 , comprising a mobile terminal.
13. A mobile terminal device comprising at least one apparatus according to claim 1 .