Method and apparatus for substantially improving power supply rejection performance in a miniature microphone assembly
AssigneeKnowles Electronics, LLC
InventorsSteven E. Boor, Frank R. Mitchell
Life of this patent
Estimating the term…
Abstract
A hybrid circuit (300) for use in a miniature microphone assembly (100) reduces power supply noise on the audio signal input (214) of an impedance buffer amplifier (200) using one or both of shielding conductors 422, 424 to reduce parasitic capacitance between signal (418) and power supply (420) conductors. A ground plane (424), an interposing conductor (422) and combinations thereof are selectively placed and coupled to either ground (232) or a low impedance signal node (216) to reduce or eliminate the undesirable parasitic capacitance.
Claims17
A miniature microphone assembly comprising:
- a substrate having a first surface and a second surface opposite the first surface, the substrate being an insulator;
- a conductive plane disposed on one of the first and second surfaces, the conductive plane partially covering the one of the first and second surfaces;
- a first conductor disposed on the first surface to be non-overlapping with the conductive plane, the first conductor to couple to an audio signal associated with the microphone assembly;
- a second conductor disposed on the insulator, the second conductor overlapping with the conductive plane, the second conductor to couple to a power source for the microphone assembly;
- and
- a shield conductor disposed on the insulator, the shield conductor overlapping the conductive plane, the shield conductor disposed between the first and second conductors.
A method of manufacturing a hybrid circuit for use in a miniature microphone assembly comprising:
- providing a substrate, the substrate having a first surface and a second surface opposite the first surface;
- disposing a first conductor on the first surface, the first conductor for coupling a signal associated with an electret audio transducer;
- disposing a second conductor on the first surface, the second conductor for coupling to a power source of the miniature microphone assembly;
- disposing a third conductor between the first and second conductors to reduce a parasitic capacitance between the first and second conductors, the third conductor coupled to one of a ground node and a low impedance signal node of a buffer amplifier;
- disposing a conductive plane on the substrate such that the conductive plane overlaps the second and third conductors and does not overlap the first conductor, the conductive plane separated from the second and third conductors by an insulator;
- and
- coupling an integrated circuit comprising an impedance buffer circuit to the substrate and one of the first and second conductors.
A hybrid circuit for use in a miniature microphone assembly comprising:
- a substrate having a first surface and a second surface opposite the first surface, the substrate being an insulator;
- a first conductor, disposed on the first surface, the first conductor for coupling to an electret audio transducer;
- a second conductor, disposed on the first surface, the second conductor to couple to a power source of the miniature microphone assembly;
- a ground plane disposed to overlap the second conductor and not overlap the first conductor;
- and
- a shield conductor, disposed on the first surface, the shield conductor disposed between the first and second conductors and overlapping the ground plane.
Dependencies are inferred from the claim text.