Internal Voltage Generator for Contactless IC Card Ripple Mitigation
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Solution Overview
Problem
Contactless IC cards face issues with ripple phenomena due to fluctuating internal voltages during encryption operations, leading to potential transmission errors.
Innovation Solution
An internal voltage generator that includes a regulator, a reference voltage generator, and a switching unit to selectively apply either the first or second internal voltage as a reference voltage based on operation modes, filtering or providing a constant voltage to mitigate fluctuations and prevent ripple transfer to the input voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the first internal voltage is used as reference voltage during encryption operations, then the internal circuit can operate with sufficient power, but ripple phenomenon occurs causing transmission errors
Solution Approach 1:
The system dynamically switches between two different reference voltage sources based on the operation mode. During encryption operations, the first reference voltage (derived from first internal voltage) is used to provide sufficient power. During normal operations, the second reference voltage (derived from second internal voltage) is used to prevent ripple phenomenon. This dynamic adaptation resolves the contradiction between power requirements and transmission reliability.
Solution Approach 2:
The reference voltage parameter is changed based on operation mode. The system generates two different reference voltages with different characteristics: one optimized for high power delivery during encryption, and another optimized for ripple-free operation during normal tasks. By switching between these parameter configurations, the system achieves both high power capability and transmission reliability as needed.
2Device complexity
If a single reference voltage is used for all operation modes, then the device complexity is reduced, but the reference voltage cannot adapt to different current consumption requirements
Solution Approach 1:
The voltage generation system is designed with multi-functionality to handle different operation modes. Two reference voltage generators are implemented, each optimized for specific current consumption scenarios. The switching unit enables the system to universally accommodate both high-current encryption operations and low-current normal operations, making the reference voltage system adaptable to all operation modes while maintaining manageable complexity.
3Device complexity
If the reference voltage is derived directly from internal voltage, then the circuit design is simplified, but fluctuations in internal voltage are transferred to the reference voltage causing ripple
Solution Approach 1:
An intermediary switching mechanism is introduced between the internal voltage sources and the reference voltage output. The switching unit acts as a mediator that selects which internal voltage-derived reference voltage to use based on operation mode. This intermediary structure allows the system to maintain simple derivation relationships while achieving stable reference voltage output by preventing fluctuation transfer during encryption operations.
Data Source
AI summary
A voltage generator of a contactless integrated circuit (IC) card includes a regulator configured to generate a first internal voltage based on an input voltage and a first reference voltage, the input voltage being received through an antenna of the contactless IC card. The voltage generator includes an internal voltage generator configured to generate a second internal voltage, the second internal voltage being used to operate an internal circuit of the contactless IC card. The voltage generator includes a reference voltage generator configured to generate a second reference voltage based on the first internal voltage, the second reference voltage being generated without regard to a fluctuation component of the first internal voltage. The voltage generator includes a switching unit configured to provide one of the first and second internal voltages as the first reference voltage in response to first and second switching control signals.