Receiver I/Q Imbalance Measurement Using Internal Testing Signals
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Solution Overview
Problem
Current communication systems face challenges in accurately measuring and correcting receiver parameters due to gain deviation, I/Q gain imbalance, I/Q quadrature deviation, and I/Q delay imbalance, which are complex to separate and correct using traditional methods, and require costly and complex testing signal generation circuits.
Innovation Solution
A method and system for measuring I/Q quadrature deviation and I/Q delay imbalance using specific testing signals in a communication receiver, involving a mixer for generating I and Q signals, and separate testing signal generating circuits for each channel, allowing for digital signal processing to calculate and correct these imbalances without the need for external testing signal devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If outside generated testing signals are used to measure receiver parameters, then measurement capability is provided, but testing device complexity and cost increase due to needing external testing signal generating devices and related circuit paths
Solution Approach 1:
The patent merges the testing signal generating circuits into the receiver itself, combining the receiver and tester functions into a single integrated device. The receiver includes an RF signal generating circuit connected to the mixer, allowing it to generate its own testing signals internally, thereby eliminating the need for separate external testing equipment and reducing overall system complexity.
Solution Approach 2:
The receiver performs self-testing by generating its own testing signals through the integrated RF signal generating circuit. The receiver measures its own parameters (I/Q gain imbalance, I/Q phase imbalance, gain deviation) using internally generated signals, eliminating dependency on external testing devices and enabling autonomous parameter characterization.
2Ease of operation
If inside generated special testing signals are used to measure receiver parameters, then testing convenience is improved, but chip area and cost increase due to requiring additional signal generating circuits
Solution Approach 1:
The RF signal generating circuit serves multiple functions: it generates the local oscillator signal for the mixer during normal reception, and also generates testing signals for parameter measurement. This multi-functionality allows the same circuit to support both signal reception and self-testing without requiring separate dedicated testing signal generators, thereby minimizing additional chip area.
Solution Approach 2:
The circuit changes its operating parameters to switch between normal reception mode and testing mode. By adjusting the frequency and characteristics of the locally generated signal, the same hardware circuit can function as both a local oscillator during reception and as a testing signal source during measurement, eliminating the need for separate testing circuitry.
3Manufacturing precision
If traditional calibration methods are used to correct gain deviation, then gain correction is achieved, but calibration complexity increases and precision may be insufficient due to requiring individual gain module calibration
Solution Approach 1:
The system uses feedback from the measured I/Q gain imbalance and I/Q phase imbalance to automatically adjust and correct gain deviations. By measuring the actual performance parameters and using this information to guide correction, the system achieves higher precision without requiring complex manual calibration procedures for each individual gain module.
Solution Approach 2:
The calibration process adjusts the operating parameters of the gain modules based on measured performance data. By changing the gain settings of modules according to the measured I/Q imbalances, the system achieves precise correction of gain deviations through parameter optimization rather than individual module calibration.
4Device complexity
If I/Q quadrature deviation and I/Q delay imbalance are measured together using traditional methods, then measurement is simplified, but separation of the two parameters is not achieved, making chip design modification difficult
Solution Approach 1:
The measurement procedure is segmented into distinct phases: first measuring I/Q gain imbalance using a first testing signal, then measuring I/Q phase imbalance using a second testing signal. This segmentation allows the total I/Q phase imbalance to be decomposed into separate contributions from quadrature deviation and delay imbalance, providing the information needed for targeted design modifications.
Solution Approach 2:
The patent performs measurements that go beyond what traditional methods do by separately characterizing I/Q gain imbalance and I/Q phase imbalance. This excessive measurement approach provides more information than needed for basic correction, enabling the separation of quadrature deviation and delay imbalance components for more precise design optimization.
Data Source
AI summary
A method and apparatus for measuring parameters of a receiver having a mixer for generating an I signal and a Q signal using an input signal, an I channel circuit for processing the I signal, and a Q channel circuit for processing the Q signal. The method includes feeding the receiver a first testing signal before the mixer. The method includes feeding the receiver a second testing signal on the I channel circuit. The method includes feeding the receiver a third testing signal on the Q channel circuit. The method includes measuring I/Q quadrature deviation and I/Q delay imbalance of the receiver using the first, the second, and the third testing signals. This separates the I/Q quadrature deviation and I/Q delay imbalance.