Inductive Comm Circuit with Tunable Tank for Band Selection

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Solution Overview

Problem

In inductive wireless communication systems, particularly in personal health applications like biomedical implants, achieving optimal resonance frequency and signal fidelity is challenging due to limitations in available capacitance, leading to degraded audio quality when higher resonance frequencies are needed.

Innovation Solution

A wireless communications device with a tank circuit, driver circuit, and tuning-drive circuit that allows selection of frequency bands by adjusting capacitance and drive strength, using a controller to connect/disconnect capacitive circuits and buffers to maintain resonance frequency stability across varying transmit levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If capacitance is increased to achieve higher resonance frequencies, then resonance frequency is improved, but available capacitance is limited leading to degraded audio quality

Engineering Contradiction:
Improveresonance frequencyVSAvoidaudio quality
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent implements dynamic adjustment of capacitance values in the tank circuit by switching between different capacitor configurations (series/parallel combinations) based on the selected frequency band. This allows the circuit to adaptively optimize capacitance for each frequency band, achieving higher resonance frequencies without degrading audio quality.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the capacitance parameter dynamically by selecting different capacitor values and configurations depending on the operating frequency band. The control circuit adjusts the effective capacitance to match the requirements of each frequency band, enabling optimal resonance frequency achievement while maintaining signal fidelity.

Inventive Principle:
Principle #35Parameter changes

2Power

If transmit level is increased to improve signal strength, then power conversion efficiency is improved, but resonance frequency stability deteriorates

Engineering Contradiction:
Improvepower conversion efficiencyVSAvoidresonance frequency stability
Core Design Contradiction:
PowerVSStability of the object's composition

Solution Approach 1:

The control circuit monitors the operating conditions and dynamically adjusts the capacitance configuration in response to transmit level changes. This feedback mechanism ensures that the resonance frequency remains stable even when power conversion efficiency varies with different transmit levels, by compensating for frequency drift through adaptive capacitance adjustment.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system employs dynamic capacitance adjustment that responds to changes in transmit level. When power conversion efficiency changes affect resonance frequency, the control circuit switches capacitor configurations to restore optimal resonance conditions, maintaining frequency stability across varying power operating points.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If multiple frequency bands are supported to enhance communication flexibility, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improvefrequency band selectionVSAvoidcircuit complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements a universal tank circuit architecture that can operate across multiple frequency bands by reconfiguring the same capacitor elements. Instead of requiring separate circuits for each frequency band, the system uses a single multi-functional tank circuit that can be tuned to different frequencies through capacitor switching, thereby supporting multiple bands without proportionally increasing complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system merges multiple capacitor elements into a single reconfigurable capacitance network that serves all frequency bands. By combining several capacitors that can be switched in series or parallel configurations, the circuit achieves multi-band operation while minimizing the total component count and overall circuit complexity compared to having separate circuits for each band.

Inventive Principle:
Principle #5Merging (Combining)

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 enhances signal fidelity and flexibility in resonance frequency selection, ensuring effective data transmission over short ranges by optimizing drive strength and capacitance, thereby improving communication quality in personal health applications.

Implementation Method 1

the RLC tank needs to have a center frequency (resonance frequency) as centered for the frequency band in which the data-carrying signal is transmitted

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 2

data communication is often effected from a transmitting circuit using an inductor, or transformer, to magnetically transfer the energy signal carrying the data to a receiving circuit

Methodology Applied
Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentEP3683973B1Circuit for inductive communications with multiple bands
Publication Date: 2023.06.21 NXP BV
  • EP3683973B1 patent drawingFigure 1
  • EP3683973B1 patent drawingFigure 2
  • EP3683973B1 patent drawingFigure 3

AI summary

Aspects are directed to a wireless communications approach in which a signal is conveyed via one of a number of particular frequency bands. In one example, a tank circuit includes an inductor and multiple capacitive circuits, and a driver circuit includes multiple buffers. One of the buffers is responsive to the input signal and another of the buffers is not responsive to the input signal. The driver circuit is configured to drive the tank circuit through a respective capacitive circuit while coupled to a respective buffer at a node of the inductor. A tuning-drive circuit drives the tank circuit for communicating in one band of a selectably-tunable frequency range. The tuning-drive circuit includes selectable (buffer and capacitor) portions configured to selectively couple to the node, for an overall drive strength and an overall tuning capacitance, and for tuning the tank circuit to a selected frequency band for wireless communication.