Variable Voltage cMUT Using Composite Signal
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Solution Overview
Problem
Existing capacitive micromachined ultrasonic transducers (cMUTs) face performance trade-offs due to the use of constant operation voltage levels for both transmission and reception modes, leading to increased complexity and cost, especially in large arrays, as they require two high voltage AC signals that need to be synchronized and cannot share the same AC bias signal.
Innovation Solution
A cMUT system and operation method utilizing an input signal with two components of different frequency characteristics, where one component generates acoustic output and the other sets the operation voltage, allowing for variable operation voltages between transmission and reception modes using a single AC signal, enabling shared bias signals across multiple elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different bias voltage levels are used for TX and RX operations with AC bias signals, then transmission and reception performance are optimized, but system complexity and cost increase due to requiring two separate high voltage AC signals and doubled wiring
Solution Approach 1:
The patent combines the TX input signal and AC bias signal into a single composite signal applied to the cMUT. The composite signal contains both the acoustic generation component (TX signal) and the operation voltage modulation component (AC bias), eliminating the need for separate signal paths and reducing wiring complexity while maintaining optimized TX and RX performance
Solution Approach 2:
The single composite signal serves multiple functions simultaneously: it acts as the TX input signal for acoustic generation, provides the AC bias for variable operation voltage, and enables mode switching between transmission and reception. This multi-functionality reduces the number of required signal lines and simplifies the overall system architecture
2Adaptability or versatility
If two high voltage AC signals are used for TX and RX operations, then variable operation voltages are achieved, but the number of wires doubles and synchronization complexity increases
Solution Approach 1:
The patent merges the TX input signal and AC bias signal into one composite signal that carries both functions. This single signal is applied to the cMUT through a single wire connection, halving the wiring requirement compared to using two separate high voltage AC signals while still achieving variable operation voltages for optimized TX and RX performance
3Device complexity
If a constant operation voltage level is used for both TX and RX operations, then system simplicity is maintained, but performance optimization is limited due to trade-offs between transmission and reception modes
Solution Approach 1:
The patent introduces dynamic operation voltage control by superimposing an AC bias signal on the DC bias voltage. The operation voltage varies dynamically between TX and RX modes, allowing optimization of performance for each mode while maintaining relatively simple system architecture through a single composite signal approach
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
This approach optimizes both transmission and reception performance, reduces system complexity, and lowers costs by allowing a single AC signal to be used, making it suitable for large arrays and applications like ultrasonic harmonic imaging.
Implementation Method 1
The alternating electrostatic force between the top electrode and the bottom electrode actuates the membrane in order to deliver acoustic energy into the medium surrounding the cMUT
Implementation Method 2
During reception an impinging acoustic wave causes the membrane to vibrate, thus altering the capacitance between the two electrodes
Data Source
AI summary
A cMUT and a cMUT operation method use an input signal that has two components with different frequency characteristics. The first component has primarily acoustic frequencies within a frequency response band of the cMUT, while the second component has primarily frequencies out of the frequency response band. The bias signal and the second component of the input signal together apply an operation voltage on the cMUT. The operation voltage is variable between operation modes, such as transmission and reception modes. The cMUT allows variable operation voltage by requiring only one AC component. This allows the bias signal to be commonly shared by multiple cMUT elements, and simplifies fabrication. The implementations of the cMUT and the operation method are particularly suitable for ultrasonic harmonic imaging in which the reception mode receives higher harmonic frequencies.