Smart Card Bidirectional Voltage Converter Without Charge Pumps
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Solution Overview
Problem
Smart cards performing fingerprint authentication face challenges in effectively booting operations without relying on charge-pumps, which can limit efficiency and area occupancy.
Innovation Solution
A bi-directional voltage converter is introduced, comprising a gate driving circuit, switching circuit, start-up circuit, and delayed clock signal generator, which enables effective booting operations by storing and boosting voltages without the need for charge-pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a charge-pump is used for booting operations in smart cards, then the booting operation can be performed, but the occupied area increases and efficiency is limited
Solution Approach 1:
The patent extracts and eliminates the charge-pump component from the smart card system. By removing this unnecessary component, the design achieves booting operations without occupying additional area, directly resolving the contradiction between booting capability and area occupancy.
Solution Approach 2:
The voltage converter circuit is designed to perform multiple functions: it converts voltages between different levels (VDD3P to VDD5P and vice versa) and simultaneously performs booting operations. This multi-functionality eliminates the need for separate charge-pump circuits, improving efficiency while reducing occupied area.
2Reliability
If a charge-pump is used for booting operations, then booting can be achieved, but device complexity increases
Solution Approach 1:
The patent merges the booting function with the existing voltage converter circuit. The same circuit that converts between VDD3P and VDD5P levels is configured to perform booting operations by controlling the switching elements and capacitors, thereby eliminating the need for separate charge-pump circuits and reducing overall device complexity.
Solution Approach 2:
The voltage converter circuit is designed to automatically perform booting operations using its own internal components (switching elements, capacitors, and control logic) without requiring external charge-pump assistance. The circuit serves itself by utilizing its voltage conversion capability to bootstrap the system.
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
The bi-directional voltage converter enhances the efficiency and reduces the occupied area in smart cards by effectively performing booting operations and supporting fingerprint authentication, while eliminating the need for charge-pumps.
Implementation Method 1
The first through fourth switching elements are switched in response to respective one of the first through fourth clock signals and store an output voltage applied to an output node in a storage capacitor coupled between a first node and a second node
Implementation Method 2
The first start-up transistor and the second start-up transistor are switched in response to a first delayed clock signal and a second delayed clock signal to provide the output voltage stored in the storage capacitor to the input node
Data Source
AI summary
A bi-directional voltage converter of a smart card includes switching elements connected between an input node and an output node and a start-up transistors whose channel width over channel length is smaller than a channel width over channel length of the switching element. The bi-directional voltage converter stores a driving voltage applied to an output node in a storage capacitor during a booting operation and provides the voltage stored in the storage capacitor to an input node. The bi-directional voltage converter may boost another driving voltage at the input node step-wisely and may perform bi-directional voltage converting with reduced occupied area and high efficiency.