RC-CR Phase Calibration Circuit for Measurement Receiver Accuracy
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Solution Overview
Problem
Measurement receivers in wireless communication systems face challenges in maintaining accurate phase difference between RC and CR paths due to mismatched loading impedance and layout variations, leading to RC-CR phase errors that affect calibration performance.
Innovation Solution
A circuit with a RC-CR phase error calibration mechanism, utilizing an array of capacitors and switches connected in parallel, adjusts the phase difference between output signals to fall within a predetermined range by controlling the switches, ensuring accurate phase shift across a wide frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RC-CR circuit is used for phase shifting in measurement receiver, then phase shift function is achieved, but phase error occurs due to mismatched loading impedance and layout variations
Solution Approach 1:
The patent applies preliminary action by performing phase error calibration before actual measurement operations. The calibration process pre-adjusts the RC and CR path phase shifts using adjustable capacitors to compensate for impedance mismatches and layout variations, ensuring accurate phase difference from the outset rather than correcting errors during operation
Solution Approach 2:
The patent implements parameter changes by making the capacitors in the RC and CR paths adjustable rather than fixed. By varying the capacitance values of these components during calibration, the phase shift characteristics of each path can be independently tuned to achieve precise phase difference and compensate for circuit variations
2Device complexity
If fixed capacitors are used in RC and CR paths, then circuit simplicity is maintained, but phase difference accuracy deteriorates due to loading impedance mismatch
Solution Approach 1:
The patent applies dynamics by transforming the static, fixed capacitor values into dynamic, adjustable parameters. The capacitors in the RC and CR paths can be adjusted during calibration to change their capacitance values, allowing the circuit to adapt to different loading conditions and achieve optimal phase difference accuracy for each specific operating condition
3Measurement precision
If RC-CR phase error calibration is performed, then phase accuracy is improved, but additional calibration time and complexity are required
Solution Approach 1:
The calibration process is performed as a preliminary action during device initialization or setup phase, separating the time-consuming calibration activity from the actual measurement operations. This ensures that once calibrated, the device operates with high phase accuracy without incurring calibration time delays during normal use
Solution Approach 2:
The calibration process employs feedback mechanisms where the actual phase difference is measured and compared against the target value, and the capacitor adjustments are made based on this feedback. This iterative feedback approach enables precise calibration while minimizing the number of adjustment steps required, thereby reducing overall calibration time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively calibrates RC-CR phase errors, enhancing the accuracy of phase shift and improving the performance of measurement receivers in factory and live mode calibrations, particularly for FD I/Q image calibration in wireless communication systems.
Implementation Method 1
the circuit comprises an array of capacitors and a plurality of switches, a first terminal of each of the array of capacitors is coupled to the first output node of the RC-CR circuit, and a second terminal of each of the array of capacitors is coupled to a ground of the circuit through a corresponding switch in the plurality of switches
Data Source
AI summary
A circuit includes a RC-CR circuit and a second circuit. The RC-CR circuit outputs a first signal at a first output node over a RC path, and a second signal at a second output node over a CR path. The second circuit is coupled to the RC-CR circuit at the first output node over the RC path. The second circuit includes an array of capacitors coupled in parallel and a plurality of switches, and each of the array of capacitors is connected, in series, to a corresponding switch in the plurality of switches. Each of the array of capacitors and its corresponding switch are coupled between the first output node and a ground. The plurality of switches is switched on or off such that the first signal and the second signal have a phase difference that falls within a predetermined phase range.