Microphone interface and method of operation

• US 8,687,823 B2
• Filed: 09/16/2010
• Issued: 04/01/2014
• Est. Priority Date: 09/16/2009
• Status: Active Grant

• Current Assignee: Knowles Electronics Llc (Knowles Corporation)
• Original Assignee: Knowles Electronics Llc (Knowles Corporation)
• Inventors: Loeppert, Peter V., Smith, Paul Fielding, Dai, Wei-Wen, Beus, Shawn
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): HAMID, AMMAR T
• Application Number:
  US12/883,454
• Publication Number:
  US 20110064246A1
• Time in Patent Office: 1,293 Days
• Field of Search: 381122-123, 381/312, 381/314, 381/318, 381/107, 381/94.1, 348/255, 348/300
• US Class Current: 381/107
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated
• CPC Class Codes: H03G 3/3026 the gain being discontinuously variable, e.g. controlled by switching

Abstract

An interface is provided between a transducer and audio processing circuitry. The interface has a switching device coupled to the transducer. The interface also has a first signal path that is selectively coupled to transducer via the switching device and includes a first output, the first signal path being configured to selectively receive input signals from the transducer, and form a first output signal at the first output by amplifying the input signals to provide a first gain. The first output is coupled to the audio processing circuitry. A second signal path is provided that is selectively coupled to the transducer via the switching device and includes a second output. The second gain is selected to be substantially larger than the first gain. The switching device is configured to switch the input signal between the first signal path and the second signal path.

Claims

1. An interface between a single transducer and audio processing circuitry, the interface comprising:

a switching device that is coupled to the single transducer and that is configured to receive input signals from the transducer;

a first signal path that is selectively coupled to the single transducer via the switching device and that includes a first output, the first signal path being configured to selectively receive the input signals from the single transducer, forms a first output signal at the first output by amplifying the input signals to provide a first gain, the first output being coupled to the audio processing circuitry;

a second signal path that is selectively coupled to the single transducer via the switching device and that includes a second output, the second signal path being configured to selectively receive the input signals from the single transducer, forms a second output signal at the second output by amplifying the input signals to provide a second gain, the second gain being selected to be substantially larger than the first gain, the second output being coupled to the audio processing circuitry;

such that the switching device is configured to switch the input signal between the first signal path and the second signal path based upon at least one measured electrical parameter of the first output signal or at least one electrical parameter of the second output signal;

wherein the first signal path provides a first voltage at the first output and the second signal path provides a second voltage at the second output, and the first voltage and the second voltage are maintained even when the first signal path or the second signal path are disconnected from the switching device.

2. An interface between a single transducer and audio processing circuitry, the interface comprising:

a switching device that is coupled to the single transducer and that is configured to receive input signals from the transducer;

a first signal path that is selectively coupled to the single transducer via the switching device and that includes a first output, the first signal path being configured to selectively receive the input signals from the single transducer, forms a first output signal at the first output by amplifying the input signals to provide a first gain, the first output being coupled to the audio processing circuitry;

a second signal path that is selectively coupled to the single transducer via the switching device and that includes a second output, the second signal path being configured to selectively receive the input signals from the single transducer, forms a second output signal at the second output by amplifying the input signals to provide a second gain, the second gain being selected to be substantially larger than the first gain, the second output being coupled to the audio processing circuitry;

such that the switching device is configured to switch the input signal between the first signal path and the second signal path based upon at least one measured electrical parameter of the first output signal or at least one electrical parameter of the second output signal;

wherein the transducer is part of a microphone assembly, wherein a property detected at an output of the microphone assembly is indicative of a switching status of the switching device.

3. An interface between a single transducer and audio processing circuitry, the interface comprising:

a switching device that is coupled to the single transducer and that is configured to receive input signals from the transducer;

a first signal path that is selectively coupled to the single transducer via the switching device and that includes a first output, the first signal path being configured to selectively receive the input signals from the single transducer, forms a first output signal at the first output by amplifying the input signals to provide a first gain, the first output being coupled to the audio processing circuitry;

a second signal path that is selectively coupled to the single transducer via the switching device and that includes a second output, the second signal path being configured to selectively receive the input signals from the single transducer, forms a second output signal at the second output by amplifying the input signals to provide a second gain, the second gain being selected to be substantially larger than the first gain, the second output being coupled to the audio processing circuitry;

such that the switching device is configured to continuously switch the input signal between the first signal path and the second signal path, the switching between the first signal path and the second signal path providing simultaneous outputs at different gains.

4. The interface of claim 3 wherein the transducer is part of a microphone assembly.

5. The interface of claim 4 wherein the first signal path functions to achieve a desired signal-to-noise ratio for the microphone assembly.

6. The interface of claim 4 wherein the second signal path prevents saturation of the microphone assembly.

7. The interface of claim 4 further including:

a processor in connection with the first signal path and the second signal path, wherein the processor selects either the first signal path or the second signal path based on an electrical parameter which is at least one selected from a group consisting of;

signal amplitude, signal-to-noise ratio, and distortion.

8. The interface of claim 7 wherein a property detected at an output of the microphone assembly is indicative of a selection status of the processor.