Synchronous Reset Phase Alignment for RF Local Oscillator Dividers
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Solution Overview
Problem
In wireless communication networks, especially those using multiple access technologies like 3G, 4G, and Wi-Fi, there is a challenge in ensuring that local oscillator signals across different receiver, transmitter, or transceiver paths are in-phase, which is crucial for functions like beamforming but often start up arbitrarily in-phase or out-of-phase, leading to phase shifts that affect signal alignment.
Innovation Solution
A phase detection circuit is implemented, using a mixer to combine input signals and filter out frequency components, with an analog-to-digital converter determining phase alignment by comparing direct current components to a reference signal, and a phase shifter adjusts signals if they are out-of-phase, ensuring all local oscillating signals are synchronized to be in-phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple frequency dividers are used to generate local oscillator signals for different transceiver paths, then the system can support multiple receiver/transmitter paths, but the local oscillator signals may start up arbitrarily in-phase or out-of-phase, causing phase misalignment
Solution Approach 1:
The patent applies preliminary action by implementing a synchronous reset mechanism that initializes all frequency dividers at a predetermined phase alignment state before operation begins. The reset signal is distributed to all divider circuits simultaneously, ensuring they start in a known in-phase condition rather than allowing arbitrary startup phases. This preliminary phase synchronization resolves the contradiction by establishing precise phase relationships before the system enters normal operation.
Solution Approach 2:
The patent employs feedback through phase detection circuits that continuously monitor the phase relationships between local oscillator signals from different frequency dividers. When phase misalignment is detected, the system generates correction signals to adjust the phase of individual dividers, maintaining precise phase alignment throughout operation. This feedback mechanism ensures that the phase precision is maintained despite the presence of multiple independent transceiver paths.
2Ease of operation
If frequency dividers operate independently without coordination, then each path can function autonomously, but phase shifts occur between dividers affecting signal alignment for beamforming and other coordinated functions
Solution Approach 1:
The patent implements a universal reset signal distribution network that serves all frequency divider circuits simultaneously. This single reset mechanism provides a common reference point for phase alignment across all independent transceiver paths, enabling them to maintain coordinated phase relationships while preserving their operational independence. The universal reset approach allows each path to function autonomously while ensuring reliable phase alignment through the shared initialization and synchronization mechanism.
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 solution effectively detects and adjusts phase shifts between local oscillating signals, ensuring they are in-phase, thereby improving signal alignment and performance in wireless communication networks, particularly in multi-chain radio frequency front-ends.
Implementation Method 1
a mixer configured to mix a first input signal having a first frequency with a second input signal having a second frequency to produce an output signal having frequency components at the sum of and the difference between the first frequency and the second frequency
Implementation Method 2
a filter connected with the output signal produced by the mixer and configured to remove one of the frequency components at the sum of the first frequency and the second frequency, thereby leaving a direct current (DC) component
Data Source
AI summary
Certain aspects of the present invention provide methods and apparatus for synchronizing frequency-divided oscillating signals associated with multiple radio frequency (RF) paths to be in-phase. For certain aspects, a reset pulse is input to synchronization logic for a particular RF path, and this logic retimes the reset pulse to a local synthesizer clock in this RF path. The retimed reset pulse drives the reset input of a local frequency divider for this RF path and is also appropriately delayed, buffered, and then daisy-chained to the synchronization logic in the next RF path to be repeated therein. By appropriately resetting the local frequency dividers using the synchronization logic in this manner, the frequency-divided oscillating signals for the RF paths are synchronized to operate in-phase with one another.