Fingerprint Sensing Circuit With Floating High-Voltage Drive
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Solution Overview
Problem
The high production cost of fingerprint identification systems due to the need for high-voltage semiconductor processes to generate high-voltage square wave signals for enhanced fingerprint signal intensity.
Innovation Solution
A fingerprint identification system utilizing a low-voltage process to generate high-voltage signals through a signal generation circuit comprising transistors, diodes, and voltage level shifters, which produce floating power and ground signals with amplitudes greater than the breakdown voltage, thereby increasing signal intensity without the need for high-voltage semiconductor components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-voltage semiconductor process is used to produce semiconductor components with high breakdown voltage, then high-voltage square wave signals can be generated to enhance fingerprint signal intensity, but the production cost increases
Solution Approach 1:
The patent changes the voltage parameter by using voltage level shifter circuits to convert low-voltage control signals into high-voltage drive signals. The level shifters translate the control signals from the low-voltage domain to the high-voltage domain, enabling the generation of high-voltage square wave signals without requiring high-voltage semiconductor components. This parameter transformation resolves the contradiction by achieving high signal intensity through voltage translation rather than through expensive high-voltage manufacturing processes.
2Reliability
If high-voltage semiconductor components are used to generate high-voltage signals, then the fingerprint signal can be enhanced, but the device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent introduces voltage level shifter circuits as intermediary components between the low-voltage control signal source and the high-voltage signal generation stage. These level shifters act as mediators that translate voltage levels without requiring the entire semiconductor fabrication process to be performed at high voltage. This intermediary approach simplifies the manufacturing process by allowing standard low-voltage processes to be used while still achieving high-voltage signal output through the intermediate translation stage.
Data Source
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AI summary
A fingerprint identification system includes: a fingerprint sensing circuit having a power supply terminal and a floating ground terminal, used for generating a first signal; and a signal generation circuit having a first output terminal and a second output terminal, wherein the first output terminal is coupled to the power supply terminal, and the second output terminal is coupled to the floating ground terminal, the signal generation circuit is used for generating a floating power signal to the power supply terminal according to the first signal, and for generating a floating ground signal to the floating ground terminal according to the first signal, wherein the floating power signal has a floating power amplitude, and the floating ground signal has a floating ground amplitude; and wherein the signal generation circuit has a breakdown voltage, and both the floating power amplitude and the floating ground amplitude are greater than the breakdown voltage.