Microphone Pre-amplifier Polarization Voltage Supply
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Solution Overview
Problem
Existing microphone systems with a two-wire interface are limited by the inability to generate the high stability and voltage needed for pre-polarized microphones, making them complex and expensive, while prior solutions cannot effectively utilize un-polarized microphones due to power constraints.
Innovation Solution
A polarization voltage supply system that transforms a partial constant input current into a high voltage level using a transformation stage, a voltage increaser stage, and a noise reduction stage, allowing un-polarized microphones to be used with a two-wire interface by generating approximately 200V from a limited input current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If pre-polarized microphone capsules are used with a two-wire interface, then the microphone system can operate with limited power, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
The microphone capsule polarizes itself by generating the required polarization voltage through its own pre-amplifier circuitry powered by the constant current from the two-wire interface, eliminating the need for external polarization supply and complex pre-polarization manufacturing processes
Solution Approach 2:
The two-wire interface serves multiple functions simultaneously: it provides power to the pre-amplifier, transmits the audio signal, and supplies the constant current needed for self-polarization, replacing the need for separate polarization wiring and reducing interface complexity
2Ease of manufacture
If un-polarized microphones are used with a two-wire interface, then manufacturing complexity is reduced, but the system cannot generate the required high stability polarization voltage from the limited input current
Solution Approach 1:
The pre-amplifier converts the constant current parameter into a high-voltage parameter through impedance transformation and voltage amplification, generating the required 200V polarization voltage with high stability from the limited 2-4mA input current
Solution Approach 2:
The pre-amplifier acts as an intermediary device that bridges the gap between the low-power two-wire interface and the high-voltage polarization requirement, using the constant current to generate both the polarization voltage and power for its own operation
3Productivity
If the available constant current is used to drive the preamplifier and cable, then the audio signal can be transmitted, but no current remains to generate the required 200V polarization voltage
Solution Approach 1:
The pre-amplifier uses only a portion of the available constant current for its own operation and cable driving, while the remaining current is sufficient to generate the high voltage needed for polarization through impedance transformation
Solution Approach 2:
The pre-amplifier transforms the current parameter into a voltage parameter, allowing the system to generate high voltage from limited current by changing the electrical parameter through active circuitry
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the use of un-polarized microphones with a two-wire interface, reducing complexity and cost, and improving audio signal reliability and quality in large systems.
Implementation Method 1
a transformation stage to transform a partial part of the constant input current on the one wire from the remote signal analyzer into an output voltage with a first voltage level
Implementation Method 2
a voltage increaser stage to increase the voltage level of the output voltage into an increased output voltage with a second voltage level
Implementation Method 3
a polarization voltage supply connected to the two wires to polarize the microphone
Data Source
Figure 1
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Figure 3
AI summary
A system (1) of at least one microphone (2) and a remote signal analyzer (3) connected to the microphone (2) with two wires (5, 6) to transmit an audio signal (Uaud) back to the analyzer (3) and to receive a constant input current (Iin) on one of the wires (5) from the analyzer (3), which microphone (2) comprises an acoustic sensor (7) and a pre-amplifier (9) powered with the constant input current (Iin) to amplify the audio signal (Uaud) from the acoustic sensor (7), wherein the microphone (2) comprises a polarization voltage supply (8) connected to the two wires (5, 6) to polarize the microphone (10), which polarization voltage supply (8) comprises: a transformation stage (11) to transform a partial part of the constant input current (Iin) on the one wire (5) from the remote signal analyzer (3) into an output voltage (Ustab) with a first voltage level and a voltage increaser stage (12) to increase the voltage level of the output voltage (Ustab) into an increased output voltage (Uhigh) with a second voltage level and a noise reduction stage (13) to provide a polarization voltage (Upol) to the acoustic sensor (7).