Passive RFID AM Data Recovery Circuit
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Solution Overview
Problem
Current RFID chips with external batteries are expensive and require a cost-effective, passive solution with sufficient read range for inventory management in industries.
Innovation Solution
A CMOS-based RF data communication device with a self-regulated power supply using RF-DC converters, voltage sensors, and shunt elements, along with an AM data recovery circuit, to convert RF signals into power and demodulate signals without external power sources, ensuring efficient energy use and reliable data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external batteries are used in RFID chips, then power supply reliability is improved, but device cost and size increase
Solution Approach 1:
The invention extracts and eliminates the external battery component from the RFID chip system. Instead of using separate battery power sources, the system harvests power from the RF signals themselves through rectification circuits, thereby removing the problematic external battery while maintaining power supply functionality
Solution Approach 2:
The RFID chip system performs self-powering by harvesting energy from incoming RF signals through on-chip rectification circuits. The system serves its own power needs internally without requiring external battery supplementation, converting received RF energy directly into usable power for chip operation
2Device complexity
If passive RFID chips are used to reduce cost, then device cost is reduced, but read range and power availability deteriorate
Solution Approach 1:
The invention changes the power availability parameter by implementing efficient on-chip power management circuits including voltage regulation and power amplification stages. These circuits optimize the conversion efficiency from harvested RF power to usable operating voltage, extending the effective read range while maintaining passive chip architecture
Solution Approach 2:
The RFID chip integrates multiple functions into a single passive device: RF signal reception, power harvesting through rectification, voltage regulation, data modulation, and communication. This multi-functional integration enables the passive chip to perform both power acquisition and data transmission tasks that would traditionally require separate components
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 minimizes costs while maintaining a satisfactory read range, enabling efficient inventory management without the need for external batteries, thus addressing the expense and labor-intensive issues of traditional RFID systems.
Implementation Method 1
The RF-DC converter is used to convert an RF signal at an input node to a power signal at an output node
Implementation Method 2
The demodulator is used to convert an incoming RF signal at an input node to a base-band signal at an output node
Implementation Method 3
The low pass filter is utilized to generate a reference signal that follows and approaches the base-band signal with a time constant
Data Source
AI summary
The present invention provides a passive RFID chip with on-chip charge pumps for generating electrical power for the chip from radio frequencies. The passive RFID chip comprises an analog portion and a digital portion. The analog portion primarily comprises a voltage sensor and an AM data detector. The digital portion comprises a state machine digital logic controller. Incoming RF signals enter the chip via external antennas. The RF signals are converted into regulated DC signals by RF-DC converters with the voltage sensor. The RF-DC converters provide power for all the on-chip components and hence the chip does not require external power supply. The incoming RF signals are demodulated by demodulators and enter the AM data detector where the envelope transitions are detected. A voltage alarm is provided to ensure the voltage level does not drop below an operational level of the chip. The logic signals and programming data are controlled by the state machine digital logic controller and the timing signals are provided by an on-chip oscillator.