Polar Transmitter Amplitude Offset Calibration Using Feedback Signals
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Solution Overview
Problem
Existing amplitude offset calibration methods for polar transmitters are inadequate, leading to worsened nonlinearity and performance issues due to amplitude offsets, which cannot be effectively addressed by Digital Pre-Distortion (DPD) technology.
Innovation Solution
A method involving obtaining multiple test feedback signals with varying amplitudes, converting them to baseband signals, and determining an amplitude offset value to calibrate and compensate for the offset in the digital domain, using existing receiver paths for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Digital Pre-Distortion (DPD) technology is used for amplitude nonlinearity calibration, then nonlinearity calibration effect is improved, but amplitude offset cannot be dealt with and calibration effect is worsened
Solution Approach 1:
The calibration process is segmented into two independent parts: amplitude offset calibration and nonlinearity calibration. The patent first performs offset calibration using test signals with different amplitudes to determine an offset value, then performs nonlinearity calibration using DPD. This segmentation allows each calibration task to be addressed by the most appropriate method without interference.
Solution Approach 2:
The patent performs amplitude offset calibration as a preliminary action before nonlinearity calibration. By determining the amplitude offset value first and compensating for it in advance, the system prepares the signal path to be free from offset effects, thereby improving the accuracy of subsequent nonlinearity calibration.
2Use of energy by moving object
If polar transmitter is used instead of direct quadrature up-conversion transmitter, then power consumption and area are reduced, but amplitude offset is introduced due to circuit structure and environmental factors
Solution Approach 1:
The patent implements a feedback-based calibration mechanism where test signals are transmitted through the polar transmitter, the output is measured, and the amplitude offset is determined by comparing the input test signals with different amplitudes against the actual output. This feedback loop enables automatic detection and compensation of the amplitude offset introduced by the polar transmitter's circuit structure and environmental factors.
Solution Approach 2:
The patent changes the operating parameters of the polar transmitter by applying test signals with different amplitudes during calibration. By observing how the transmitter responds to these varying input parameters, the system can determine the amplitude offset and subsequently compensate for it, thereby eliminating the harmful effect while maintaining the power-efficient polar architecture.
3Measurement precision
If amplitude offset calibration is performed using multiple test signals with different amplitudes, then calibration accuracy is improved, but calibration process complexity increases
Solution Approach 1:
The patent employs periodic action by using a sequence of test signals with different amplitudes in a systematic calibration routine. The transmitter is switched to test mode, where it periodically transmits these calibrated test signals, measures the output, determines the offset, and then returns to normal operation. This periodic calibration approach achieves high accuracy while keeping the complexity manageable through automation and structured timing.
Data Source
AI summary
The present disclosure provides an amplitude offset calibration method. The method includes: obtaining at least two test feedback signals, where the test feedback signals are analog signals obtained by a transmitter in a test mode according to a test signal, at least two test signals in one-to-one correspondence to the at least two test feedback signals are digital signals pre-generated by the transmitter, and amplitudes of the at least two test signals are different; obtaining at least two corresponding baseband signals according to the at least two test feedback signals, where the baseband signals are a digital signal, and the baseband signals are in one-to-one correspondence to the test feedback signals; and determining an amplitude offset value according to the at least two test signals and the at least two baseband signals.