Transceiver Phase Synchronization via Beat Signal Mixing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
RF communication systems, such as direct conversion quadrature radios, suffer from impairments like quadrature errors and local oscillator leakage, which degrade performance and are difficult to calibrate due to similar spectral characteristics between transmit and observation mixers, leading to imperfect calibration and high complexity, power consumption, and long calibration times.
Innovation Solution
A transceiver design that uses a transmit channel and an observation channel with different local oscillator frequencies to observe and correct transmit channel impairments independently, employing a digital modulator to compensate for frequency differences and a phase adjustment circuit to synchronize local oscillators, allowing for efficient calibration without pre-calibrating the observation channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the same local oscillator frequency is used for both transmit and observation channels, then spectral characteristics are similar making calibration difficult, but using different frequencies increases device complexity
Solution Approach 1:
The patent changes the frequency parameter of the local oscillator in the observation channel to be different from the transmit channel frequency. This parameter change creates distinct spectral characteristics between the two channels, enabling accurate calibration by allowing the observation channel to independently measure transmit impairments without being confounded by similar spectral patterns.
2Productivity
If observation channel is pre-calibrated, then calibration complexity is reduced, but calibration time increases and noise floor is elevated
Solution Approach 1:
The patent extracts the observation channel from the calibration process by using a different frequency, allowing it to serve as an independent measurement tool rather than requiring it to be pre-calibrated. This extraction enables the observation channel to directly measure transmit impairments without introducing additional noise or requiring time-consuming pre-calibration steps.
3Measurement precision
If phase synchronization is not implemented, then device complexity is lower, but calibration precision deteriorates
Solution Approach 1:
The patent implements phase synchronization through a feedback mechanism where the system measures the phase relationship between transmit and observation local oscillators and adjusts accordingly. This feedback ensures accurate phase relationship measurement, which is critical for precise calibration of quadrature errors and other phase-dependent impairments.
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 enables effective calibration of transmit channel impairments independently of observation channel impairments, reducing noise floor and calibration time, and achieving phase synchronization, thus improving RF communication system performance.
Implementation Method 1
generating a beat signal based on the transmit local oscillator signal and the observation local oscillator signal
Implementation Method 2
phase adjustment circuit configured to generate a beat signal based on the transmit local oscillator signal and the observation local oscillator signal
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method and apparatus for phase adjustment of a RF transceiver is disclosed. Based on a first local oscillator signal and a second local oscillator signal, a beat signal that indicates the frequency and phase relationship between the first and second local oscillator signals can be generated. Using the beat signal, changing phase relationship between the first and second local oscillator signals can be cumulatively taken account for using phase averaging to allow quick restoration to observation of a previously observed channel.