Transmitter Local Oscillator Leakage Calibration
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Solution Overview
Problem
Existing calibration methods for local oscillator leakage in transmitters are time-consuming and inefficient, affecting communication systems by interfering with transmission signals.
Innovation Solution
A method involving a transmitter with in-phase and quadrature signal paths, low pass filters, and calibration units is used to optimize compensation values through spectrum analysis of single-frequency signals, allowing for rapid and accurate calibration of local oscillator leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used to compensate for local oscillator leakage, then the transmission signal quality is improved, but the calibration process becomes time-consuming
Solution Approach 1:
The calibration process is segmented into two independent parts: baseband circuit calibration and front-end modulation circuit calibration. Each part has its own calibration unit and compensation value, allowing them to be calibrated separately and quickly without requiring full-system iterative adjustment, thus reducing total calibration time while maintaining signal quality.
Solution Approach 2:
The patent performs preliminary calibration by setting specific compensation values in the calibration units before actual transmission. The baseband circuit is calibrated first with a first compensation value, then the front-end modulation circuit is calibrated with a second compensation value. This preliminary setup enables rapid compensation for local oscillator leakage without time-consuming iterative adjustments during operation.
2Object-generated harmful factors
If the local oscillator is isolated from the mixer and low-noise amplifier, then leakage is reduced, but the device complexity increases
Solution Approach 1:
The patent extracts the leakage compensation function into separate calibration units that are independently configured in the baseband circuit and front-end modulation circuit. Instead of requiring complex physical isolation structures, the harmful leakage effect is taken out and compensated through dedicated calibration units with adjustable compensation values, simplifying the overall transmitter structure while effectively reducing leakage.
Solution Approach 2:
The calibration units act as intermediaries between the local oscillator and the signal paths. Rather than implementing complex physical isolation, the calibration units with compensation values serve as mediators that cancel out the leakage effects through signal processing, achieving leakage reduction without increasing structural complexity.
Data Source
AI summary
The present application provides a method for calibrating a transmitter. The transmitter includes an oscillator, a first signal path, and a second signal path. The first signal path and the second signal path include a first calibration unit preceding a first low pass filter and a second low pass filter, and a second calibration unit succeeding the first low pass filter and the second low pass filter. The calibration method includes: by configuring the first calibration unit and the second calibration unit and sending a transmission signal, and performing frequency analysis upon the transmission signal to obtain a frequency analysis result, to generate an optimized first compensation value for the first calibration unit and an optimized second compensation value for the second calibration unit.