RFID Voltage Regulator Circuit Without Quiescent Current
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Solution Overview
Problem
Existing voltage regulator circuits for RFID tags consume quiescent current, are complex, and occupy large die area, limiting their power efficiency and reading range.
Innovation Solution
A power-efficient voltage regulator circuit for RFID tags utilizing a control circuit with a cross-coupled transistor pair, impulse current source, and sensing circuit to regulate output voltage without quiescent current, transformers, or inductors, and external references, achieving voltage regulation by controlling current flow through a driving element and sensing output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional voltage regulator circuits (LDO, switching regulator with comparator) are used, then voltage regulation function is achieved, but quiescent current consumption increases power dissipation
Solution Approach 1:
The patent employs periodic pulse-width modulation (PWM) control where the switching element operates in periodic on/off cycles. The duty cycle of these periodic pulses is adjusted based on feedback from the sensing circuit to maintain regulated output voltage, eliminating continuous quiescent current consumption while preserving voltage regulation through time-averaged control.
Solution Approach 2:
The sensing circuit directly utilizes a portion of the output voltage to generate feedback signals that automatically control the switching element. This self-regulating mechanism eliminates the need for external reference voltages and continuous bias currents, allowing the regulator to maintain stable operation without external power sources or quiescent current consumption.
2Measurement precision
If operational amplifiers and voltage references are included in the regulator circuit, then voltage regulation precision is improved, but device complexity and die area increase
Solution Approach 1:
The patent extracts and eliminates complex components such as operational amplifiers, voltage references, and error amplifiers from the regulator circuit. Instead, it uses a simplified sensing circuit that directly monitors output voltage and generates control signals for the switching element, achieving voltage regulation precision without the complexity and die area of traditional components.
Solution Approach 2:
The sensing circuit creates a simplified functional copy of the voltage regulation control mechanism found in complex regulators. Rather than using full operational amplifiers and reference circuits, the patent implements a lightweight sensing and feedback system that replicates the essential voltage regulation function with minimal components, reducing die area while maintaining control precision.
3Reliability
If shunt limiter is used to set output voltage level, then voltage regulation is achieved, but excess power is wasted especially when target output voltage is low
Solution Approach 1:
The patent replaces continuous shunt limiting with periodic switching control. The switching element operates in pulsed cycles, transferring energy to the output only when needed to maintain the target voltage level. This periodic energy transfer eliminates continuous power dissipation through shunt resistors, significantly reducing power waste especially when output voltage is low.
Solution Approach 2:
The sensing circuit provides continuous feedback on the output voltage level to the control circuit. When the output voltage reaches the target level, the feedback signal automatically reduces or stops switching activity, preventing over-regulation and excess power dissipation. This closed-loop feedback mechanism ensures energy-efficient voltage control without continuous power waste.
4Use of energy by moving object
If larger resistor values are used to reduce quiescent current in static comparator circuits, then power consumption decreases, but resistor size becomes impractical for RFID chip integration
Solution Approach 1:
The patent removes the static comparator and its associated large-value resistors from the circuit. Instead, it uses a dynamic sensing approach where small-signal transistors and capacitors monitor output voltage and generate control signals. This extraction of the comparator eliminates the need for impractically large resistors while maintaining voltage regulation functionality through dynamic rather than static comparison.
Solution Approach 2:
The patent changes the operating parameters of the sensing circuit from static high-impedance operation to dynamic low-impedance switching operation. By using small transistors that switch periodically rather than large resistors that continuously conduct, the circuit achieves low quiescent current consumption with compact component sizes suitable for RFID chip integration.
Data Source
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AI summary
A voltage regulator circuit for RFID circuit utilizing a high efficiency circuit topology to minimize power consumption to provide only required current to regulate output voltage. The voltage regulator circuit does not consume quiescent current which minimizes power consumption. It does not contain inductor, transformer, op-amp, voltage and current reference which reduces complexity and die area. The voltage regulator circuit comprises a driving element, a control circuit and a sensing circuit. The driving element drives controlled current to output to ramp up the voltage. The sensing circuit measures voltage at the output and sends signal to the control circuit if the voltage reaches target value set by the internal parameters of the components. The control circuit stops the driving element when output voltage reaches the threshold minimizing current required to regulate voltage.