Radio Receiver IQ Imbalance Correction from Thermal Noise Correlation
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Solution Overview
Problem
Conventional radio receivers face low correction accuracy for IQ imbalance due to incomplete factors such as transmitter IQ imbalance and limited frequency reference signals, while existing solutions increase circuit size and production cost with reference signal generators.
Innovation Solution
A radio receiver design that includes an antenna, low-noise amplifier, quadrature demodulator, ADCs, power calculators, correlation value calculator, correction parameter generator, corrector, and controller, which calculates and corrects IQ imbalance using thermal noise modeling and gain control signals to improve accuracy without increasing circuit size or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference signal generator is provided to improve correction accuracy of IQ imbalance, then correction accuracy is improved, but circuit size and production cost are increased
Solution Approach 1:
The radio receiver uses its own thermal noise as the reference signal for IQ imbalance correction, eliminating the need for an external reference signal generator. The correction unit extracts thermal noise from the received signal and uses it to calculate correction parameters, allowing the system to serve itself without additional hardware.
Solution Approach 2:
Thermal noise acts as an intermediary between the received signal and the correction process. Instead of using a dedicated reference signal generator, the system uses the naturally occurring thermal noise in the signal path as a mediator to enable IQ imbalance correction without adding circuit complexity.
2Device complexity
If conventional digital circuit correction is used, then circuit size is kept small, but correction accuracy is low due to incomplete factors
Solution Approach 1:
The invention converts thermal noise, which is traditionally considered a harmful interference factor, into a beneficial reference signal for correction. By utilizing the thermal noise already present in the system, the method achieves accurate correction without adding circuit complexity, turning a disadvantage into an advantage.
3Measurement precision
If reference signal is used for correction, then correction accuracy is improved, but the reference signal exists only in limited frequency reducing accuracy
Solution Approach 1:
The thermal noise-based correction method is universally applicable across all frequency ranges where thermal noise exists. Unlike dedicated reference signals that are limited to specific frequencies, thermal noise is present across the entire operational bandwidth, making the correction method versatile and frequency-independent.
Data Source
AI summary
According to one embodiment, a radio receiver includes an antenna, a low-noise amplifier (LNA), a quadrature demodulator, an analog-to-digital converter (ADC), first and second power calculators, a correlation value calculator, a correction parameter generator, a corrector, a demodulator, and a controller. The antenna receives a signal. The LNA amplifies the received signal. The quadrature demodulator demodulates the amplified signal. The ADC converts analog IQ into digital IQ. The first and second power calculators calculate the first and second powers, respectively. The correlation value calculator calculates a correlation value between the digital IQ. The correction parameter generator generates a correction parameter based on the first and second power expected values, and the correlation value between the digital IQ. The corrector performs a linear transform operation. The demodulator demodulates the corrected IQ. The controller generates a gain control signal. The LNA is operated on the basis of the gain control signal.