Antenna Impedance Modulation via Charge Pump Segmentation
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Solution Overview
Problem
The existing impedance modulation methods for UHF contactless integrated circuits completely neutralize the production of continuous voltage by the charge pump, leading to rapid voltage depletion during data transmission periods, which limits the maximum communication distance with the reader.
Innovation Solution
Modulating the impedance of the antenna circuit by applying a short-circuit to the output of the first pump stage, allowing the subsequent pump stages to continue supplying the continuous voltage, thereby maintaining voltage production during impedance modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a short-circuit is applied to the output of the charge pump to modulate antenna impedance, then the antenna impedance modulation is achieved, but the continuous voltage production is completely neutralized leading to rapid voltage depletion
Solution Approach 1:
The charge pump is segmented into multiple stages (first stage, second stage, third stage). The short-circuit switch is applied only to the output of the first stage, allowing the second and third stages to continue operating and producing voltage, thus resolving the contradiction between impedance modulation and voltage maintenance
Solution Approach 2:
The short-circuit action is localized to only the first stage of the charge pump rather than affecting the entire charge pump output. This localized application allows impedance modulation at the antenna interface while preserving voltage production in the remaining stages
2Reliability
If the charge pump is completely short-circuited for impedance modulation, then the modulation depth is maximized, but the communication distance is limited due to voltage depletion
Solution Approach 1:
By segmenting the charge pump into multiple stages and applying the short-circuit only to the first stage, the patent achieves sufficient modulation depth for reliable communication while maintaining voltage production in subsequent stages to extend communication distance
Solution Approach 2:
Instead of completely short-circuiting the entire charge pump, the patent applies partial short-circuiting only to the first stage, which is sufficient for achieving the required modulation depth while avoiding complete voltage depletion
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
This approach extends the communication distance and reduces voltage depletion, enabling longer data transmission periods while maintaining power supply to the integrated circuit.
Implementation Method 1
In the presence of an electric field E emitted by a reader RD1 schematically shown in the figure, antenna signals S1, S2 appear on the conductors W1, W2
Implementation Method 2
The primary charge pump PMP is driven by the signals S1, S2, used as pump signals, and supplies a continuous voltage Vcc
Implementation Method 3
When the signal Sm(DTx) is 1, the short-circuit of the charge pump causes a modulation of the antenna circuit impedance and consequently a modulation of its reflection coefficient
Data Source
AI summary
A method for modulating the impedance of an antenna circuit supplying pump signals to a charge pump comprising at least one first pump stage and one last pump stage, the last pump stage supplying a continuous voltage. The output of the first pump stage is short-circuited by means of a switch and the last pump stage goes on pumping electric charges and supplying the continuous voltage. Application in particular to RFID passive transponders.