Wireless Transceiver Calibration Circuit Gain Adjustment
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Solution Overview
Problem
Wireless transceivers face challenges in achieving desired transmission power due to inaccuracies in RF analog circuits, process variations, and differences in circuit board layout, which existing power setting values cannot effectively address.
Innovation Solution
A calibration circuit and method that adjust the target gain of the RF circuit by measuring power differences between input signals received through a coupling path and the reception path, and subsequently adjusting the baseband amplifier and digital circuit to calibrate the transmission power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing power setting values are used for the transmitter, then the device structure remains simple, but the transmission power cannot reach the desired level due to RF analog circuit inaccuracies, process variation, and circuit board layout differences
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements before actual operation. The system pre-determines correction values by measuring the actual transmission power at different gain settings and storing these calibration data. During operation, the pre-calibrated correction values are applied to compensate for RF circuit variations, achieving accurate power control without adding complex real-time adjustment mechanisms.
Solution Approach 2:
The calibration circuit utilizes the device's own transmission path and reception path to perform self-calibration. The system generates test signals internally, measures the actual power through the existing RF circuits and antenna, and automatically computes correction values. This self-service approach eliminates the need for external calibration equipment while achieving accurate power control.
2Manufacturing precision
If calibration circuits and methods are introduced to calibrate the wireless transceiver, then transmission power accuracy is improved, but the device complexity increases
Solution Approach 1:
The calibration circuit is designed with multi-functionality, serving both as a calibration system and a normal signal transmission system. The same transmission path, reception path, and signal processing circuits are used for both calibration measurements and regular operation. This universal design allows the calibration function to be integrated without requiring separate dedicated hardware, thereby minimizing the increase in device complexity.
Solution Approach 2:
The system implements feedback by measuring the actual transmission power through the reception path and comparing it with the expected power levels. The measured power values are fed back to compute correction factors that adjust the gain settings. This feedback mechanism enables automatic compensation for RF circuit variations, achieving accurate power control through a relatively simple closed-loop system.
3Measurement precision
If multiple gain setting values are tested to determine correction values, then the power calibration accuracy is improved, but the calibration time increases
Solution Approach 1:
The system applies partial action by selecting a limited number of representative gain setting values for calibration testing, rather than testing every possible power level. Typically, calibration is performed at a few key gain settings (e.g., minimum, medium, maximum), and the correction values are interpolated or extrapolated for intermediate levels. This approach achieves sufficient calibration accuracy while significantly reducing the calibration time compared to exhaustive testing.
Data Source
AI summary
A calibration circuit and a calibration method for a wireless transceiver are provided. The wireless transceiver includes a transmission path and a reception path, and the transmission path includes a radio frequency (RF) circuit and a baseband amplifier. The calibration method includes the following steps: setting a target gain of the RF circuit according to a first gain setting value; receiving a first input signal through a coupling path and the reception path; measuring first power of the first input signal; setting the target gain of the RF circuit according to a second gain setting value; receiving a second input signal through the coupling path and the reception path; measuring second power of the second input signal; calculating a power difference between the first power and the second power; and adjusting at least one of the baseband amplifier and a digital circuit according to the power difference.