Smart Card Voltage Circuit for Contact and Contactless Authentication
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Solution Overview
Problem
Smart cards face challenges in generating internal voltage for fingerprint authentication in both contact and contactless modes, requiring efficient voltage management across varying levels and modes to ensure optimal operation of circuit components.
Innovation Solution
An internal voltage generation circuit incorporating a first and second contact switch, switched capacitor converters, a bidirectional switched capacitor converter, a mode selector, and a control signal generator, which selectively switches and adjusts voltages based on mode and voltage levels to provide suitable driving voltages for fingerprint recognition and processor operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a simple voltage switching mechanism is used, then device complexity is reduced, but the ability to provide various voltage levels for different modes and components is insufficient
Solution Approach 1:
The voltage generation circuit is segmented into multiple independent modules: a first voltage generation path for contact mode operation, a second voltage generation path for contactless mode operation, and a bidirectional switched capacitor converter that can operate in both directions. Each module handles specific voltage conversion tasks, allowing the system to provide various voltage levels adaptably while keeping each module's complexity manageable through clear functional division.
2Reliability
If separate voltage generation circuits are used for contact and contactless modes, then mode-specific voltage requirements are met, but device complexity increases
Solution Approach 1:
The bidirectional switched capacitor converter is designed with multi-functionality to serve both contact mode and contactless mode voltage generation requirements. This single converter can operate in forward direction for contactless mode and in reverse direction for contact mode, eliminating the need for completely separate voltage generation circuits while maintaining reliable operation for both modes through unified design.
3Productivity
If voltage levels are not optimized for different components, then circuit design is simplified, but component performance and power consumption are suboptimal
Solution Approach 1:
Different voltage levels are provided to different components based on their specific requirements: the fingerprint recognition sensor receives a first voltage level optimized for its operation, while the processor receives a second voltage level optimized for its performance. This local quality approach ensures each component operates at optimal efficiency while the voltage management complexity is handled by the automated control logic that selects appropriate voltage paths based on operational mode.
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 smart cards to operate effectively in both contact and contactless modes by generating appropriate driving voltages, optimizing power consumption and component performance across different voltage levels, ensuring reliable fingerprint authentication.
Implementation Method 1
a switched capacitor converter, a bidirectional switched capacitor converter, a mode selector, and a control signal generator. The first contact switch selectively switches a contact voltage to a first node based on a first switching enable signal, in a contact mode. The second contact switch selectively switches the contact voltage to a second node based on a second switching enable signal, in the contact mode. The switched capacitor converter steps down a contactless voltage induced by an electromagnetic (EM) wave received from the card reader to provide a contactless mode first driving voltage to the first node in a contactless mode
Implementation Method 2
The bidirectional switched capacitor converter, connected to the first node and the second node, in the contactless mode, steps down the contactless mode first driving voltage at the first node to provide a contactless mode second voltage to the second node and, in the contact mode, either steps down a contact mode first driving voltage at the first node to provide a contact mode second driving voltage to the second node, or boosts a contact mode second driving voltage at the second node based on a level of the contact voltage to provide a boosted voltage to the first node
Data Source
AI summary
An internal voltage generation circuit of a smart card to perform fingerprint authentication and a smart card includes a first contact switch, a second contact switch, a switched capacitor converter and a bidirectional switched capacitor converter. The first contact switch selectively switches a contact voltage to a first node based on a first switching enable signal, in a contact mode. The second contact switch selectively switches the contact voltage to a second node based on a second switching enable signal, in the contact mode. The bidirectional switched capacitor converter steps down a first driving voltage of the first node to provide a second voltage to the second node in the contactless mode and either steps down the first driving voltage or boosts a second driving voltage of the second node based on a level of the contact voltage to provide a boosted voltage to the first node in the contact mode.