Quadrature Phase Controller for Zero-IF I/Q Phase Accuracy
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Solution Overview
Problem
Direct conversion receivers with a zero-IF structure face challenges in maintaining a precise 90° phase difference between in-phase and quadrature-phase signals due to manufacturing, voltage, and temperature variations, leading to deteriorated signal-to-noise ratio and receiving sensitivity.
Innovation Solution
A quadrature signal phase controller using two phase shifters and control signals to variably control the phase difference between in-phase and quadrature-phase signals, improving the image rejection ratio and precise characteristic control by adjusting the phases of these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a zero-IF direct conversion receiver structure is used, then the circuit structure becomes simpler and easier to implement as a single IC, but the phase difference between in-phase and quadrature-phase signals cannot be precisely maintained at 90° due to manufacturing process, supply voltage, and operating temperature variations
Solution Approach 1:
The patent implements a feedback mechanism where the phase difference between in-phase and quadrature-phase signals is continuously monitored and adjusted. A phase detector detects the actual phase difference, and a control signal is generated to adjust the phase shifters accordingly, ensuring the phase difference remains at 90° despite manufacturing variations, voltage changes, or temperature fluctuations.
Solution Approach 2:
The patent uses variable phase shifters that can dynamically change their phase shift parameters based on operating conditions. By adjusting the phase shift amount through control voltages or digital control words, the system compensates for deviations from the ideal 90° phase difference caused by manufacturing tolerances, supply voltage variations, or temperature changes.
2Reliability
If the phase difference between in-phase and quadrature-phase signals deviates from 90°, then the circuit remains simple, but the signal-to-noise ratio and receiving sensitivity deteriorate
Solution Approach 1:
The patent employs feedback control where the phase detector continuously monitors the phase difference and generates correction signals to maintain optimal 90° phase relationship. This feedback loop ensures high signal-to-noise ratio and receiving sensitivity by automatically compensating for phase deviations without requiring overly complex manual adjustment mechanisms.
Solution Approach 2:
The phase control system is designed to self-adjust and maintain optimal performance automatically. The phase detectors and control circuits work autonomously to detect and correct phase deviations, eliminating the need for external calibration or complex manual intervention, thus achieving high reliability with manageable complexity.
3Manufacturing precision
If fixed phase shift values are used in phase shifters, then the circuit design is simpler, but the image rejection ratio cannot be optimized under varying operating conditions
Solution Approach 1:
The patent implements dynamic phase shifters that can adjust their phase shift amount in real-time based on operating conditions such as temperature, supply voltage, and signal characteristics. This dynamic adjustment capability allows the system to maintain optimal image rejection ratio across varying conditions, unlike fixed phase shifters that would require multiple versions for different operating points.
Solution Approach 2:
The patent utilizes controllable phase shifters where the phase shift parameter can be varied through control voltages or digital control words. This allows the system to optimize image rejection ratio by adjusting phase shift values to compensate for environmental variations, manufacturing tolerances, and operating condition changes, achieving high precision without sacrificing adaptability.
Data Source
AI summary
A quadrature signal phase controller includes a first phase shifter and a second phase shifter. The first phase shifter generates phase shifted first in-phase differential output signals and phase shifted first quadrature-phase differential output signals. The second phase shifter generates phase shifted second in-phase differential output signals and phase shifted second quadrature-phase differential output signals. Each of the first and second phase shifters increases or decreases the phase difference between the first in-phase differential output signals and the second quadrature-phase differential output signals, and the phase difference between the second in-phase differential output signals and the first quadrature-phase differential output signals, in response to a change in a level of the first control signal and a change in a level of the second control signal.