Differential microphone circuit
View Patent ↗An apparatus for a portable electronic device for receiving a jack of a headset, the jack including a set of lines, the set of lines including at least one audio line, a ground signal and a microphone signal line, the apparatus comprising a set of switches for receiving the ground signal line and the microphone signal line and a sensing circuit for reducing induced noise from the headset, wherein the sensing circuit is located between the set of switches and the microphone signal line and ground signal line.
1. An apparatus for a portable electronic device for receiving a jack of a headset, the jack including a set of lines, the set of lines including at least one audio line, a ground signal and a microphone signal line, the apparatus comprising:
a set of switches to receive the ground signal line and the microphone signal line of the jack; and
a sensing circuit to reduce induced noise from the headset;
wherein the sensing circuit is located between the set of switches and the microphone signal line and ground signal line of the jack.
2. The apparatus of claim 1 wherein the sensing circuitry comprises a Kelvin sensing circuit.
3. The apparatus of claim 1 wherein the set of switches are connected to a pair of microphone lines within the portable electronic device.
4. The apparatus of claim 3 wherein the pair of microphone lines comprises a MIC+ line and a MIC− line.
5. The apparatus of claim 4 wherein a pre-amplifier is connected to the set of switches via the MIC+ line and the MIC− line.
6. The apparatus of claim 1 further comprising a video path connected to the microphone signal line.
7. The apparatus of claim 6 wherein the video path is connected to the microphone signal line via a switch.
8. The apparatus of claim 1 wherein the set of switches includes a ground switch to connect a ground reference voltage to one of the ground signal line and the microphone signal line.
9. The apparatus of claim 1 wherein the set of switches and the sensing circuit are integrated with a chip.
10. The apparatus of claim 9 wherein the chip comprises a switch matrix.
11. A portable electronic device comprising:
an audio port configured to receive a plug of an external audio device, the plug including at least one audio line, a ground signal and a microphone signal line;
a set of switches electrically connected to the audio port and configured to receive the ground signal line and the microphone signal line of the plug; and
sensing circuitry to reduce induced noise from the headset and configured between the set of switches and the microphone signal line and ground signal line of the plug.
12. The portable electronic device of claim 11 wherein the sensing circuitry comprises a Kelvin sensing circuit.
13. The portable electronic device of claim 11 wherein the set of switches are connected to a pair of microphone lines within the portable electronic device.
14. The portable electronic device of claim 13 wherein the pair of microphone lines comprises a MIC+ line and a MIC− line.
15. The portable electronic device of claim 14 wherein a pre-amplifier is connected to the set of switches via the MIC+ line and the MIC− line.
16. The portable electronic device of claim 11 further comprising a video path connected to the microphone signal line.
17. The portable electronic device of claim 16 wherein the video path is connected to the microphone signal line via a switch.
18. The portable electronic device of claim 11 wherein the set of switches includes a ground switch to connect a ground reference voltage to one of the ground signal line and the microphone signal line.
19. The portable electronic device of claim 11 wherein the set of switches and the sensing circuit are integrated with a chip.
20. The portable electronic device of claim 19 wherein the chip comprises a switch matrix.