RF Transceiver Phase Interferometer Calibration
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Solution Overview
Problem
Current RF transceiver systems for beam forming and steering face challenges in calibrating phase and amplitude adjustments across multiple antenna elements, particularly in mass production environments with tighter tolerances and higher power output requirements, leading to performance variations and increased physical size due to built-in test circuits that introduce undesired couplings.
Innovation Solution
The implementation of switchable transmit and receive RF processing paths with switchable feedback paths and RF combiners allows for calibration and linearization of RF paths by coupling phase and amplitude adjusted signals to RF combiners, enabling efficient calibration and linearization of target paths without the need for extensive feedback paths or additional test circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If built-in test circuits are added for calibration, then calibration capability is improved, but physical size increases and undesired couplings are introduced
Solution Approach 1:
The patent makes existing RF paths (transmit and receive paths) perform calibration functions in addition to their primary functions. By using the same RF processing paths for both normal operation and calibration, the system eliminates the need for separate dedicated test circuits, thereby reducing physical size and avoiding additional couplings while maintaining calibration capability
Solution Approach 2:
The transceiver system performs calibration using its own existing RF paths and components without requiring external test equipment or separate calibration circuits. The system calibrates itself by utilizing the transmit and receive paths that are already present, making the calibration process self-contained and eliminating the need for additional dedicated calibration infrastructure
2Power
If power amplifiers operate in non-linear region for higher output power, then power output is improved, but phase and amplitude distortion increases
Solution Approach 1:
The patent applies calibration adjustments to phase and amplitude control blocks before the signal reaches the power amplifier. By pre-adjusting the phase and amplitude characteristics during calibration mode, the system compensates for the non-linear effects that will occur when the amplifier operates in saturation mode during normal high-power transmission
Solution Approach 2:
The patent implements a feedback mechanism where a portion of the RF signal from the power amplifier output is fed back through the RF combiner to the phase and amplitude control blocks. This feedback loop allows the system to monitor and adjust phase and amplitude characteristics dynamically, maintaining linearity even when operating in the non-linear region for higher power output
3Manufacturing precision
If separate feedback paths are added for each transmit path, then linearization capability is improved, but device complexity and couplings increase
Solution Approach 1:
The patent combines feedback from multiple transmit paths using an RF combiner into a single aggregated signal. Instead of requiring separate feedback processing for each transmit path, the combiner merges all feedback signals into one path that can be processed by shared phase and amplitude control blocks, thereby achieving linearization without proportionally increasing device complexity
Solution Approach 2:
The RF combiner and phase/amplitude control blocks serve multiple functions: they handle both normal signal processing and calibration/linearization operations. The same control blocks that adjust phase and amplitude during calibration are also used during normal operation to maintain linearity based on feedback, eliminating the need for dedicated separate circuits for each function
Data Source
AI summary
Methods and devices for streamlining phase and amplitude calibration and linearization in RF transceiver circuits including a plurality of switchable transmit and receive processing paths is presented. According to one aspect, switchable feedback paths are provided that can selectively feedback a portion of a transmitted RF signal or a test RF signal for use in the calibration. According to another aspect, the switchable feedback paths include combination of switches and couplers to selectively combine feedback from one or more of the switchable feedback paths. According to another aspect, the switchable feedback paths reuse portions of the receive paths of the plurality of switchable transmit and receive processing paths. The switchable feedback paths can be used to provide a combined feedback RF signal based on one or more transmitted RF signals that can be used as a digital pre-distortion feedback for linearization of the one or more transmitted RF signals.