Microphone unit with internal A/D converter

• US 20110096945A1
• Filed: 12/29/2010
• Published: 04/28/2011
• Est. Priority Date: 02/02/2001
• Status: Active Grant

• Current Assignee: TDK Corporation
• Original Assignee: Epcos Pte Limited (TDK Corporation)
• Inventors: Mucha, Igor, Fürst, Claus Erdmann, Stenberg, Lars
• Granted Patent: US 8,649,528 B2
• Time in Patent Office: Days
• US Class Current: 381/120
• CPC Class Codes: H04R 19/04 Microphones H04R19/01 takes precedence

Abstract

The present invention relates to a microphone assembly comprising a microphone assembly casing having a sound inlet port and a transducer for receiving acoustic waves through the sound inlet port. The transducer converts the received acoustic waves to analog audio signals. The assembly according to the present invention further comprises an electronic circuit positioned within the microphone assembly casing, said electronic circuit comprising a pre-amplifier and an analog-to-digital converter preferably in form of a sigma-delta modulator so as to convert amplified analog audio signals to digital audio signals.

Claims

1. A microphone assembly, comprising:

a microphone assembly casing having a sound inlet port;

a transducer for receiving acoustic waves through the sound inlet port, and for converting received acoustic waves to analog audio signals, said transducer being positioned within the microphone assembly casing;

an electronic circuit positioned within the microphone assembly casing, said electronic circuit comprising a signal path defined by a cascade of

a pre-amplifier for amplifying analog audio signals from the transducer, and

a sigma-delta modulator for providing digital audio signals; and

a filter means in the signal path between the pre-amplifier and the sigma-delta modulator, the filter means preventing low frequency components from reaching the sigma-delta modulator,

wherein the pre-amplifier, the sigma-delta modulator, and at least part of the filter means are integrated on a chip so as to form a monolithic integrated circuit.

2. The microphone assembly according to claim 1, wherein the filter means is a high-pass filter.

3. A portable unit, comprising:

the microphone assembly according to claim 1, said microphone assembly being connected to a pure digital signal processor for further signal processing.

4. The portable unit according to claim 3, wherein the portable unit is selected from the group consisting of hearing aids, assistive listening devices, mobile recording units, such as MP3 players, and mobile communication units, and

the mobile communication units include at least one of mobile phones and cellular phones.

5. The microphone assembly according to claim 1, wherein the filter means is a band-pass filter.

6. The microphone assembly according to claim 5, wherein the amplifier forms part of a monolithic integrated circuit further comprising the pre-amplifier, at least part of the filter means and the sigma-delta modulator.