Parallel Transistor Receiving Circuit for Ultrasonic Sensor Noise Suppression
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Solution Overview
Problem
Conventional sensor devices for ultrasonic wave reception experience noise due to gate-drain capacitance coupling in transistors, leading to fluctuations in terminal voltage and increased signal attenuation, which complicates accurate detection of ultrasonic waves.
Innovation Solution
The sensor device employs a configuration of multiple transistors with reduced element sizes connected in parallel to minimize noise, along with filters to blunt control signals and a differential amplification process to cancel phase noise, allowing for efficient noise cancellation without compromising impedance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the element sizes of transistors 232 and 233 are reduced to suppress noise, then noise suppression is improved, but impedances (on-resistances) of the transistors are increased
Solution Approach 1:
The patent divides a single transistor into multiple transistors (232 and 233) that operate in parallel. Each transistor has reduced element size to minimize gate-drain capacitance coupling and suppress noise, while the parallel configuration maintains the required impedance characteristics by distributing the electrical load across multiple devices.
Solution Approach 2:
The patent combines multiple transistors (232 and 233) with reduced individual sizes into a parallel configuration. This merging approach allows each transistor to contribute to the overall conductivity, maintaining the required impedance characteristics while benefiting from the reduced noise of smaller individual elements.
2Ease of operation
If transistors 232 and 233 are turned on in reception operation, then switching function is improved, but terminal voltage of piezoelectric sensor fluctuates due to gate-drain capacitance coupling
Solution Approach 1:
The patent segments the switching function across multiple transistors (232 and 233) instead of using a single transistor. This segmentation reduces the gate-drain capacitance coupling effect on the piezoelectric sensor, thereby suppressing terminal voltage fluctuations while maintaining effective switching control for reception operation.
3Measurement precision
If wait time for reception operation is extended to allow noise attenuation, then measurement precision is improved, but productivity is decreased
Solution Approach 1:
The patent applies preliminary action by reducing the element sizes of transistors 232 and 233 before reception operation begins. This pre-configured reduction in gate-drain capacitance coupling minimizes noise generation at the source, allowing accurate ultrasonic wave detection to commence immediately without requiring extended wait time for noise attenuation.
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 configuration effectively suppresses noise generated during reception operations, shortening the wait time for accurate ultrasonic wave detection and improving signal quality by canceling noise components through phase shifting and differential amplification.
Implementation Method 1
a piezoelectric sensor 210, a transmission circuit 220, and a receiving circuit 230
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A receiving circuit (10) includes an amplifier (15) which amplifies receiving signals (SP, SN) of a piezoelectric sensor (2), and a plurality of transistors (11a, 11b) or (12a, 12b), which are connected in parallel to between one end of the piezoelectric sensor (2) and one end of the amplifier (15), and are turned on with phase shift when switching is performed to receiving operations.