Split Output Shunt Regulator for RFID FRAM Stability
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Solution Overview
Problem
Passive RFID tags using EEPROM memory are inadequate for high-throughput applications due to slow data transfer rates, and FRAM memory, while suitable for higher speeds, faces challenges in the RFID environment with process variations, temperature changes, and intermittent power supply.
Innovation Solution
A shunt regulator driven by an RF rectifier with split outputs is used to power RFID circuitry, including FRAM memory, with a capacitor between the rectifier output and ground, and a resistor divider and amplifier circuit to regulate power delivery and discharge, ensuring stable operation across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If FRAM memory is used to increase data throughput, then speed is improved, but reliability deteriorates due to sensitivity to process variations, temperature changes, and intermittent power supply
Solution Approach 1:
The power supply system is segmented into two independent paths: a regulated path providing stable voltage to FRAM memory and other sensitive circuits, and an unregulated path providing raw power to other RFID circuits. This segmentation isolates the FRAM memory from power supply variations, enabling high-speed operation while maintaining reliability.
Solution Approach 2:
A regulator circuit acts as an intermediary between the rectifier output and the FRAM memory. The regulator receives unregulated power from the rectifier and provides cleaned, stable voltage to the FRAM memory, filtering out process variations, temperature effects, and power interruptions before they reach the sensitive memory circuit.
2Reliability
If a regulator circuit is added to stabilize power supply, then reliability is improved, but device complexity increases
Solution Approach 1:
The power supply is divided into regulated and unregulated segments, with the regulator only servicing critical circuits like FRAM memory. This selective regulation minimizes the complexity increase while maximizing reliability benefits for the most sensitive components.
Solution Approach 2:
The regulator circuit is designed to serve multiple functions: voltage stabilization, noise filtering, and power management for the FRAM memory and associated circuits. This multi-functionality justifies the added complexity by consolidating multiple power-related functions into a single circuit block.
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 robust and efficient power management for RFID tags, stabilizing voltage across temperature changes and ensuring reliable operation of FRAM memory, even with intermittent power supply, enhancing data throughput and system reliability.
Implementation Method 1
A shunt regulator driven by an RF rectifier having split outputs
Implementation Method 2
The shunt regulator includes a capacitor coupled between the first rectifier output and ground
Implementation Method 3
a first diode having an anode coupled to the input node, a second diode having an anode coupled to the input node
Data Source
AI summary
A shunt regulator for an RFID tag chip is powered from split outputs from the RF rectifier, including a first output for providing a power delivery path to on-chip circuits and a second output for providing a discharge-regulation path. The shunt regulator includes a capacitor coupled between the first output and ground. The shunt regulator further includes an input node for receiving a power supply voltage from the rectifier split outputs, a first diode having an anode coupled to the input node, a second diode having an anode coupled to the input node, a resistor divider circuit and amplifier coupled between a cathode of the first diode and ground, transistor having a control terminal coupled to an output of the resistor divider and amplifier circuit, and a current path coupled between a cathode of the second diode and ground.