Passive Transponder Charging Circuit with Orthogonal Resonant Coils
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Solution Overview
Problem
Existing passive transponders, such as those used in immobilizer key circuits, face limitations in range and current requirements, and purely passive RFID transponders lack a reliable energy source, making them inefficient and position-dependent.
Innovation Solution
A passive transponder with a charging circuit comprising multiple parallel resonant circuits and rectifiers, which are orthogonally aligned to absorb energy from an electromagnetic field, charging a supply voltage capacitor, enabling efficient energy absorption and operation independent of antenna alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a purely passive transponder design is used, then the device complexity is reduced and battery support is eliminated, but the operational range is limited and performance becomes position-dependent
Solution Approach 1:
The patent introduces a third spatial dimension by adding a second coil oriented orthogonally to the first coil. This orthogonal arrangement allows the transponder to absorb electromagnetic energy from any direction in three-dimensional space, eliminating the position-dependency limitation of single-coil designs and expanding the operational range without adding battery support.
Solution Approach 2:
The patent segments the energy absorption function into multiple independent parallel resonant circuits, each with its own coil and rectifier. This segmentation allows each circuit to independently absorb energy from different spatial directions, and the combined output provides reliable power supply regardless of the transponder's orientation relative to the reader.
2Reliability
If multiple parallel resonant circuits are added to improve energy absorption, then the operational range and alignment independence are enhanced, but the device complexity increases
Solution Approach 1:
The patent merges multiple parallel resonant circuits into a unified charging circuit architecture where all circuits charge a common supply voltage capacitor. This merging approach allows the system to benefit from multiple coils for improved alignment independence while maintaining a relatively simple overall structure through shared components.
Solution Approach 2:
Each parallel resonant circuit serves multiple functions: it acts as an independent energy absorption antenna, a resonant amplifier at the operating frequency, and a voltage rectification source. This multi-functionality reduces the need for separate components and justifies the added complexity by delivering significant performance improvements.
3Device complexity
If the transponder operates without battery support, then the device complexity and power requirements are reduced, but a reliable energy source becomes critical for consistent operation
Solution Approach 1:
The transponder is designed to be self-sufficient by using passive energy harvesting from the reader's electromagnetic field. The multiple parallel resonant circuits automatically absorb and rectify energy from the field, charging the supply voltage capacitor without requiring external battery support or active power management, thus achieving reliable operation through self-service energy collection.
Solution Approach 2:
The patent implements preliminary energy accumulation by charging the supply voltage capacitor through multiple parallel resonant circuits before the transponder needs to operate. This preliminary action ensures that sufficient energy is stored in advance to power the transponder's operations, making the system reliable without battery support.
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 solution provides a reliable and efficient energy supply for the transponder, enhancing its operational range and independence from battery support, allowing for consistent performance even with unfavorable alignment and low field intensities.
Implementation Method 1
the supply voltage capacitor is charged by means of an induced voltage in the parallel resonant circuits
Implementation Method 2
a first rectifier, which is interconnected with the first node, and the supply voltage capacitor
Data Source
AI summary
In one embodiment, a passive transponder comprising a first circuit comprising a first attenuator, the first circuit configured to receive a first signal from at least one base station and coupled to a first node, a first rectifier coupled to the first node, the first rectifier configured in a forward direction to charge a first capacitor, and the first capacitor coupled to the first rectifier, the first capacitor configured to receive a charge from the attenuator sufficient for powering the passive transponder.