CFO Correction Circuit for Multi-Antenna RF Receiver
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Solution Overview
Problem
Conventional RF receivers with antenna diversity face challenges in accurately correcting carrier frequency offset (CFO) due to noisy phase values and discontinuities in phase measurements, which can lead to reduced sensitivity and inefficiency, especially in applications like IoT systems with stringent power and cost constraints.
Innovation Solution
The implementation of a CFO correction circuit that uses a demodulator to provide a switch signal for antenna selection and includes separate loops for phase difference estimation and removal, along with CFO estimation and removal, to accurately correct CFO and minimize discontinuities, effectively mimicking the single-antenna case even in multi-antenna systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional CFO correction methods are used in multi-antenna systems, then antenna diversity can be implemented, but phase measurement discontinuities and noise reduce CFO correction precision
Solution Approach 1:
The patent segments the CFO correction process into distinct phases: phase difference estimation, phase unwrapping to remove discontinuities, and CFO calculation. By dividing the correction process and applying specific handling to each segment, the system maintains precision despite using multiple antennas.
Solution Approach 2:
The patent introduces phase unwrapping as an intermediary step between phase measurement and CFO calculation. This intermediate processing removes discontinuities and noise effects, providing a clean phase difference value that enables precise CFO correction while maintaining multi-antenna operation.
2Reliability
If multiple antennas are used to improve signal reliability, then reception quality can be enhanced, but system complexity and power consumption increase
Solution Approach 1:
The patent extracts and processes only the necessary phase difference information from multi-antenna signals for CFO correction, rather than processing all signal aspects. This selective extraction maintains reliability benefits while limiting the increase in circuit complexity to only what is needed for phase comparison and unwrapping.
3Measurement precision
If phase difference estimation is performed to correct CFO in multi-antenna systems, then CFO precision can be improved, but discontinuities in phase samples reduce estimation accuracy
Solution Approach 1:
The patent performs phase unwrapping as a preliminary action before CFO estimation. By removing discontinuities and stabilizing the phase samples in advance, the subsequent CFO calculation operates on clean, continuous data, ensuring high precision without being affected by phase wraparound artifacts.
Data Source
AI summary
An apparatus includes a radio-frequency (RF) receiver for receiving an RF signal using a plurality of antennas. The RF receiver includes a demodulator to provide a switch signal to cause the RF receiver to use an antenna in the plurality of antennas. The RF receiver further includes a carrier frequency offset (CFO) correction circuit that uses an estimation of the carrier frequency offset and an estimation of phase differences to remove the carrier frequency offset.