Bootstrap Boosting Circuit for RFID Tags
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Solution Overview
Problem
Conventional boosting circuits for RFID tags suffer from reduced boosting efficiency due to transistor threshold potential losses and leakage currents, which hinder the effective boosting of input signals.
Innovation Solution
The proposed boosting circuit employs a bootstrap operation to boost the output terminal node and uses oxide semiconductors to minimize off-state current, thereby enhancing boosting efficiency and reducing potential losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional boosting circuits with transistors are used, then voltage boosting is achieved, but threshold potential losses reduce boosting efficiency
Solution Approach 1:
A bootstrap capacitor is introduced as an intermediary element to transfer and maintain high voltage potential from the output terminal back to the gate terminal of the transistor. This mediator enables the transistor to operate at elevated gate voltages without suffering cumulative threshold losses, thereby resolving the contradiction between achieving high output voltage and minimizing energy loss.
Solution Approach 2:
The bootstrap capacitor pre-charges the gate terminal to a high voltage level before the transistor needs to switch. This preliminary action ensures that the transistor operates with sufficient gate-over-drive voltage throughout the switching cycle, preventing threshold potential losses from degrading boosting efficiency.
2Power
If multiple unit boosting circuits are connected in series, then higher voltage boosting is achieved, but leakage current increases and reduces boosting efficiency
Solution Approach 1:
The bootstrap capacitor acts as an intermediary that isolates the transistor from cumulative threshold losses across multiple series-connected stages. By maintaining proper gate voltage levels through capacitive coupling, it enables more stages to be connected in series without proportionally increasing leakage current losses, thus achieving higher boosted voltage with improved efficiency.
3Loss of energy
If transistor gate voltage is increased to overcome threshold losses, then boosting efficiency improves, but transistor breakdown risk increases
Solution Approach 1:
The bootstrap capacitor creates an equipotential relationship between the output terminal and gate terminal, maintaining a consistent voltage difference that keeps the transistor in its safe operating region. This approach achieves high boosting efficiency by eliminating threshold losses without subjecting the transistor to excessive voltage stress that would cause breakdown.
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 enhanced boosting circuit achieves improved efficiency by preventing potential drops and reducing leakage currents, allowing for higher output potentials with fewer stages, thus enabling higher integration and reliability in RFID tags.
Implementation Method 1
the input signal is boosted up by capacitive coupling of a capacitor to which a clock signal or an inverted clock signal is input
Implementation Method 2
uses oxide semiconductors to minimize off-state current
Data Source
AI summary
One object is to provide a boosting circuit whose boosting efficiency is enhanced. Another object is to provide an RFID tag including a boosting circuit whose boosting efficiency is enhanced. A node corresponding to an output terminal of a unit boosting circuit or a gate electrode of a transistor connected to the node is boosted by bootstrap operation, so that a decrease in potential which corresponds to substantially the same as the threshold potential of the transistor can be prevented and a decrease in output potential of the unit boosting circuit can be prevented.