Phase-Shift RF Transmitter for Implantable Devices
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Solution Overview
Problem
Cochlear implant systems face challenges in achieving efficient power conversion and transfer due to bulky housings, high power requirements, and frequent battery replacement, largely because traditional power conversion techniques require additional circuitry and generate unwanted harmonics, leading to inefficiencies and electromagnetic interference.
Innovation Solution
An RF telemetry transmitter system using phase delay techniques to control power levels, eliminating the need for a voltage regulator and associated components, and employing a push-pull configuration with phase shifting circuitry and a transformer network to suppress harmonics and ensure accurate power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional power conversion techniques (class D, E/F, G, H, or S transmitter with voltage regulator) are used, then power can be transferred to the implanted device, but the system requires additional circuitry, inductors, and capacitors that increase device complexity, power consumption, and size
Solution Approach 1:
The patent extracts and eliminates the voltage regulator circuitry from the traditional power conversion system. By using phase shift modulation directly at the power amplifier stage, the invention removes the need for separate voltage regulation components (inductors, capacitors, control circuits), thereby reducing device complexity while maintaining power transfer capability
Solution Approach 2:
The patent merges the power amplification and voltage control functions into a single integrated stage. The power amplifier simultaneously performs both power delivery and voltage regulation through phase shift modulation, eliminating the need for separate voltage regulator components and reducing overall system complexity
2Device complexity
If PWM technique is used to control transmitter power output, then voltage regulator is eliminated, but even and odd higher order harmonics are imposed on the carrier signal that increase filtering circuitry complexity and reduce power efficiency
Solution Approach 1:
The patent applies phase shift modulation selectively at the power amplifier stage rather than using broad-spectrum PWM. This localized modulation approach controls power output without generating the broad spectrum of harmonics characteristic of PWM, thereby maintaining power efficiency while simplifying the filtering requirements
Solution Approach 2:
The patent changes the modulation parameter from duty cycle (PWM) to phase shift angle. This parameter transformation fundamentally alters the spectral characteristics of the output signal, eliminating the even and odd harmonics generated by PWM while maintaining the ability to control power output levels
3Device complexity
If PWM technique is used to control transmitter power output, then voltage regulator is eliminated, but control of duty cycle becomes difficult as it approaches zero, preventing accurate power control across the entire available range
Solution Approach 1:
The patent transforms the control parameter from duty cycle (which becomes difficult to control near zero) to phase shift angle (which provides linear and uniform control across the entire range). This parameter transformation enables accurate power control from minimum to maximum output levels without the difficulties associated with PWM duty cycle control
4Device complexity
If higher order harmonics are not suppressed, then filtering circuitry complexity is reduced, but harmonic currents decrease the power efficiency of the transmitter circuitry and generate EMI
Solution Approach 1:
The patent applies phase shift modulation that inherently suppresses harmonic generation at the source rather than requiring post-generation filtering. By controlling the phase shift angle, the system prevents harmonic currents from being generated in the first place, thereby maintaining power efficiency without requiring complex filtering circuitry
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 results in a compact, low-power, highly efficient RF telemetry transmitter that accurately controls power levels across a wide range, reducing waste and ensuring proper device operation while minimizing harmonic interference and electromagnetic interference.
Implementation Method 1
a high frequency carrier signal, which is applied to the external device coil, is coupled to the implanted device coil. This coupling is akin to the flux coupling seen in transformers.
Implementation Method 2
An RF telemetry transmitter system using phase delay techniques to control power levels
Implementation Method 3
employing a push-pull configuration with phase shifting circuitry and a transformer network to suppress harmonics and ensure accurate power transfer
Data Source
AI summary
Systems and methods for efficiently transmitting power using a high frequency (e.g., RF) telemetry transmitter are provided. The telemetry transmitter may include a fixed clock source (which may provide a fixed clock signal), telemetry phase shift circuitry (which may include switching circuitry and phase shifting circuitry), and a push-pull network. The telemetry phase shift circuitry generates a phase shifted clock signal that is phase shifted with respect to the fixed clock signal. The fixed and phase shifted clock signals may drive the switching circuitry to produce a high frequency signal that is passed through the push-pull network. The power or magnitude of the high frequency signal is based on the phase delay between the fixed clock signal and the phase shifted clock signal.