Variable Gain IQ Correction Circuit for Amplitude and Phase Balance
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Solution Overview
Problem
Existing systems for correcting amplitude and phase imbalances in IQ signals are prone to variations due to fabrication tolerances and operating conditions, and may result in signal loss or inefficiency.
Innovation Solution
A correction circuit comprising a plurality of variable gain circuits that can amplify, attenuate, or pass signals to achieve balanced amplitudes and phases, with each gain circuit's settings determined by phase and amplitude imbalance parameters, and optionally including calibration circuitry for adaptive correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If known correction systems (e.g., system 200 with capacitive tuning) are used to correct phase imbalance, then phase correction is achieved, but amplitude imbalance cannot be corrected and additional gain/loss correction is required
Solution Approach 1:
The patent combines phase correction and amplitude correction into a single integrated correction circuit. The complex correction circuit applies both phase shift and gain adjustment simultaneously through a unified structure, eliminating the need for separate capacitive tuning and gain/loss correction stages that would otherwise be required.
Solution Approach 2:
The correction circuit performs multiple functions simultaneously: it corrects both phase imbalance and amplitude imbalance in the IQ signals through a single device. The circuit is designed to handle both correction tasks that would traditionally require separate dedicated circuits.
2Measurement precision
If amplitude clipping is used to resolve amplitude and phase imbalance (U.S. Pat. No. 6,054,883A), then imbalance correction is achieved, but information loss occurs on the amplitude of the signals
Solution Approach 1:
Instead of clipping the amplitude signal which destroys information, the patent changes the approach by using variable gain adjustment. The correction circuit applies precise gain factors to the I and Q signals based on calculated correction parameters, maintaining the full amplitude information while achieving the required imbalance correction.
3Ease of manufacture
If correction systems are implemented with fixed component values, then manufacturing is simplified, but variations in component values due to fabrication tolerances and operating temperature degrade correction accuracy
Solution Approach 1:
The correction circuit incorporates variable gain elements that can dynamically adjust their parameters based on operating conditions. This allows the circuit to compensate for temperature drift and fabrication variations by adapting the correction factors in real-time, rather than relying on fixed component values that would degrade in performance under varying conditions.
4Reliability
If multiple separate correction circuits are used for amplitude and phase correction, then each correction function is specialized, but the overall system complexity increases
Solution Approach 1:
The patent merges the amplitude correction and phase correction functions into a single integrated correction circuit. This unified approach reduces the overall number of components and interconnections required, simplifying the system while maintaining the specialized correction functions through careful design of the correction algorithm and circuit topology.
Data Source
AI summary
A correction circuit for correcting an amplitude imbalance and a phase imbalance between an in-phase signal and a quadrature signal, the correction circuit comprising a plurality of variable gain circuits configured to provide in-phase and quadrature signals having balanced amplitudes and balanced phases, wherein each variable gain circuit is configured to apply a gain to amplify, attenuate or to pass a signal.