Phase Switching PLL for Rapid Beamforming Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Beamforming systems face performance degradation due to slow phase shifting, which is insufficient to allow phase changes between consecutive data frames without affecting transmission or reception, necessitating faster and improved phase control.
Innovation Solution
A phase-locked loop (PLL) system is implemented for each antenna element, utilizing a modulation signal with pulses defined by the desired phase shift for open-loop phase control and a phase skew circuit to maintain the phase shift through a time relationship between reference and feedback signals, enabling rapid phase adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If local oscillator beamforming is used to control phase of each antenna element, then phase control is achieved, but the phase shifting speed is too slow to allow changes between consecutive data frames
Solution Approach 1:
The phase control function is segmented into two independent paths: a fast open-loop path using an auxiliary control input that directly modulates the oscillator phase, and a traditional closed-loop path using the primary control input. This segmentation allows the system to achieve rapid phase changes through the open-loop path without being constrained by the slower feedback response time, while the closed-loop path maintains long-term accuracy.
Solution Approach 2:
The auxiliary control input applies preliminary phase modulation to the oscillator before the feedback loop can respond. By anticipating the required phase change and applying it directly through the auxiliary input, the system achieves fast phase switching that occurs before the traditional feedback mechanism would complete its adjustment, enabling phase changes between consecutive data frames.
2Speed
If faster phase control is implemented using open-loop modulation, then phase shifting speed improves, but phase accuracy may be compromised without feedback control
Solution Approach 1:
The system dynamically switches between open-loop and closed-loop control modes based on the timing requirements. During critical intervals between data frames, the open-loop auxiliary control provides fast response. During stable operation intervals, the closed-loop primary control maintains long-term accuracy. This dynamic operation allows the system to exploit the strengths of both control approaches at different times.
Solution Approach 2:
The auxiliary control input acts as an intermediary that bridges the gap between the requirement for fast phase switching and the need for accurate phase control. It provides the fast initial response that the traditional feedback loop cannot deliver, while the main feedback loop subsequently refines and maintains the phase accuracy, effectively mediating between speed and precision requirements.
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The phase-locked loop (PLL) presented herein controls the phase of the output of the PLL. To that end, the PLL includes an oscillator that generates an output signal at an output of the PLL responsive to a comparison between a reference signal input to the PLL and a feedback signal derived from the output signal. To control the phase of the output signal, a modulation signal is applied to one input of the oscillator, separate from the reference signal input, where the modulation signal comprises one or more pulses having a total area defined based on the desired phase shift. To maintain the desired phase shift at the output of the PLL, the PLL also sets a time relationship between the reference signal and the feedback signal based on the desired phase shift.