RFID Tag Power Rectifier With Synchronous MOSFET Control
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Solution Overview
Problem
Passive RFID tags face challenges in efficiently converting low-level RF signals into usable voltage due to the intermittent nature of RF waves and the need for high-voltage operations, which complicates power management and memory operations.
Innovation Solution
A power rectifier system utilizing a pair of complementary MOS transistors with synchronized, out-of-phase control signals to maximize energy harvest efficiency, allowing for efficient conversion of RF signals into usable DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If charge pumps are used to increase output DC voltage for high-voltage operations, then high voltage (up to 12 volts) can be achieved for memory programming and erasing, but the device complexity increases and energy efficiency decreases
Solution Approach 1:
The patent changes the operating parameters of the rectifier circuit by using synchronous switching of MOSFETs with carefully controlled gate voltages and timing signals. This allows the circuit to achieve high voltage output (up to 12V) through parameter optimization rather than complex circuit topology, thereby reducing device complexity while maintaining voltage capability.
Solution Approach 2:
The invention employs dynamic control of MOSFET switching states using synchronized gate signals that respond to the RF input waveform. This dynamic operation allows the rectifier to efficiently convert RF energy to high voltage DC without requiring static complex circuit structures, resolving the contradiction between voltage capability and circuit complexity.
2Ease of operation
If the RF signal amplitude is low (approximately 200 millivolts), then passive tag operation is enabled without batteries, but the available power is insufficient to operate the tag circuitry requiring one volt or more
Solution Approach 1:
The patent transforms the energy parameters from low-voltage RF signals (200mV) to high-voltage DC output (1V to 12V) through a synchronized rectifier circuit. By changing voltage and power parameters through controlled MOSFET switching, the system enables passive tag operation while providing sufficient power for all circuitry operations.
Solution Approach 2:
The rectifier circuit recovers energy from the RF signal that would otherwise be lost during conversion. By using synchronous switching with properly timed gate control, the circuit maximizes energy transfer efficiency from the RF input to DC output, ensuring that sufficient power is extracted from the low-amplitude RF signal to operate the passive tag.
3Adaptability or versatility
If the RF wave transmission is intermittent (ceases without notice), then reader flexibility is improved, but the power supply to the tag becomes unstable
Solution Approach 1:
The synchronized rectifier circuit is designed to quickly respond to the presence or absence of RF signals by using pre-biased MOSFET gates and synchronous switching. This preliminary preparation allows the circuit to rapidly transition between power states, maintaining reliability during intermittent transmission by readying the power conversion path before RF signals cease.
Solution Approach 2:
The rectifier circuit maintains continuous power conversion capability even when RF transmission is intermittent. Through synchronous switching and proper biasing, the circuit ensures that power conversion action continues as long as RF energy is present, and transitions smoothly when transmission ceases, thereby maintaining power supply reliability despite reader flexibility.
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 enhances the energy harvest efficiency of RFID tags, enabling reliable operation even with low RF signal amplitudes and ensuring continuous power supply for circuit operations.
Implementation Method 1
operation of passive RFID tag converting the low-level RF waveform to a usable voltage requires a rectifier circuit that can generate usable voltage quickly and efficiently
Data Source
AI summary
The present disclosure provides a power rectifier for a Radio Frequency Identification tag circuit. The rectifier is constructed from a pair of complementary MOS transistors. Gates of the transistors have predetermined voltages applied to them. The applied voltages bias the transistors to near their active operating region. During the same time additional control signals are applied to the gates of the transistors, the control signals are synchronous, but out of phase, with each other.