PLL Phase Difference Control Using Feedback Divider Injection
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Solution Overview
Problem
Existing RF phase shifter technologies face limitations in frequency band and phase control precision, particularly in wireless power transmission, where precise phase shifting is required for beamforming, and analog-based solutions are inadequate.
Innovation Solution
Modifying a phase locked loop circuit by adding a feedback divider and a phase adjustment current to the loop current, which is applied through an adder circuit, allowing for internal phase shifting without the need for a separate RF phase shifter, thereby enhancing phase shift resolution and reducing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an analog phase shift circuit using a transmission line is used, then phase shifting function is achieved, but loss increases and frequency band limitation occurs
Solution Approach 1:
The patent replaces the analog transmission line-based phase shift circuit with a digital phase shift implementation. The phase shifting function is achieved through digital signal processing and control logic rather than physical transmission line adjustments, eliminating the inherent losses and frequency limitations of analog approaches while maintaining precise phase control capability
Solution Approach 2:
The patent changes the operating parameters by using digital control signals to adjust phase shift amounts dynamically. Instead of relying on fixed transmission line lengths, the system uses programmable parameters stored in memory that can be adjusted without physical changes, enabling precise phase control across different frequency bands without the losses associated with analog transmission lines
2Reliability
If an analog phase shift circuit is used, then phase shifting is achieved, but phase control precision is limited
Solution Approach 1:
The patent substitutes digital control mechanisms for analog phase adjustment circuits. By using digital signal processors and programmable logic, the system achieves higher phase control precision through binary-encoded phase values and precise timing control, eliminating the resolution limitations inherent in analog voltage or physical position-based control
Solution Approach 2:
The patent segments the phase control into discrete, programmable steps. The phase shift amount is divided into multiple selectable levels that can be precisely controlled through digital signals, allowing for fine-grained phase adjustment that exceeds the precision capabilities of continuous analog control systems
3Adaptability or versatility
If a separate RF phase shifter is added, then phase shifting function is achieved, but device complexity increases
Solution Approach 1:
The patent merges the phase shifting function with existing signal processing circuits in the wireless transmission terminal. The phase control logic is integrated into the existing RF signal path rather than being implemented as a separate external component, reducing overall system complexity while maintaining full phase shifting capability through shared hardware resources
Solution Approach 2:
The patent implements a universal control mechanism that handles both frequency control and phase shifting functions through a single integrated system. The same digital control infrastructure used for frequency synthesis is also employed for phase adjustment, eliminating the need for separate dedicated phase shifter hardware and reducing overall device complexity
Data Source
AI summary
Internal phase shifting is achieved by adding a feedback divider to a feedback loop of a phase locked loop circuit configured to determine a transmission frequency of a wireless transmission terminal and adding a phase adjustment current to a loop current. Since the phase adjustment current is applied to an adder circuit, a phase difference is maintained even when the feedback loop is in a stable state, and accordingly, an output of the feedback divider maintains the phase difference with a reference frequency as intended by the phase adjustment current applied to the adder circuit.