Split Local Oscillator Path With Phase-Synced Frequency Dividers
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Solution Overview
Problem
Wireless communication devices face limited battery life due to high current consumption by oscillators in their local oscillator paths, especially when full capacity is not needed, leading to inefficient power usage and phase synchronization issues in split LO paths.
Innovation Solution
A fully split local oscillator path is implemented, using a master frequency divider and multiple slave frequency dividers, with phase detection and cross-coupled switches to synchronize phases and reduce power consumption by selectively powering on segments based on system requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the local oscillator path is split into multiple frequency dividers, then current consumption is reduced by selective activation, but phase synchronization between segments becomes problematic
Solution Approach 1:
The local oscillator path is divided into multiple frequency divider segments that can be independently activated. Each segment contains a frequency divider and associated circuitry that can be powered on or off based on system requirements, allowing current consumption to be reduced by activating only the necessary segments.
Solution Approach 2:
A phase detection mechanism is implemented to monitor phase relationships between the master and slave frequency divider segments. Based on the detected phase difference, a control signal is generated to activate the cross-coupled switch, creating a feedback loop that maintains phase synchronization automatically.
2Use of energy by moving object
If a fully split LO path is implemented with master and slave frequency dividers, then power consumption is reduced through selective segment activation, but device complexity increases due to additional synchronization circuitry
Solution Approach 1:
The LO path is segmented into master and slave frequency dividers with independent power control. This allows the system to activate only the necessary segments based on operating conditions, reducing overall power consumption while maintaining the required functionality.
Solution Approach 2:
The phase detection and control logic are integrated into the existing LO path architecture. The cross-coupled switch is strategically placed to provide phase synchronization without requiring separate, dedicated synchronization circuits, thereby minimizing the increase in device complexity.
3Reliability
If cross-coupled switches are used to synchronize slave frequency divider phase, then phase synchronization is achieved, but current consumption increases due to additional active components
Solution Approach 1:
The cross-coupled switch is activated periodically or on-demand based on phase detection requirements rather than continuously. The control logic activates the switch only when phase synchronization is needed, allowing the switch to remain in a low-power state during normal operation and reducing overall current consumption.
Solution Approach 2:
The phase synchronization function is extracted as a separate, independently controllable feature. The cross-coupled switch and its control logic operate independently from the main signal path, allowing phase synchronization to be enabled or disabled based on system requirements without affecting the core LO functionality.
Data Source
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AI summary
A method for reducing average current consumption in a local oscillator (LO) path is disclosed. An LO signal is received at a master frequency divider and a slave frequency divider. Output from the master frequency divider is mixed with an input signal to produce a first mixed output. Output from the slave frequency divider is mixed with the input signal to produce a second mixed output. The second mixed output is forced to be in phase with the first mixed output.