Transmitter Baseband Loop Calibration for DC Offset Nulling
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Solution Overview
Problem
Large direct current (DC) offsets in electronic devices, such as mobile phones and tablets, can degrade communication quality, necessitating effective calibration methods to maintain reliable transmission.
Innovation Solution
An electronic device with a digital-to-analog converter (DAC), transmitter front-end (TX FE), amplifier, and analog-to-digital converter (ADC) uses a swap circuitry to form a baseband loop for DC offset calibration, allowing for precise calibration by comparing digital values in both normal and swapped states, thereby nullifying the DC offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC offset calibration is performed using traditional methods, then communication quality can be maintained, but hardware costs increase and device complexity increases
Solution Approach 1:
The amplifier and ADC components are made multi-functional by enabling them to participate in both normal signal transmission and DC offset calibration operations. The swap circuitry allows these components to be reused for calibration purposes, eliminating the need for dedicated calibration hardware and reducing overall device complexity while maintaining communication quality
Solution Approach 2:
The system performs self-calibration by using its own existing components (amplifier, ADC, swap circuitry) to measure and correct its own DC offset without requiring external calibration equipment. The baseband processor calculates the DC offset value and applies correction autonomously, reducing hardware requirements and simplifying the overall system
2Reliability
If DC offset calibration is performed frequently, then communication quality is maintained, but loss of time occurs due to calibration operations
Solution Approach 1:
The system performs preliminary DC offset calibration during manufacturing or initial setup, establishing a baseline correction value that can be applied immediately upon device activation. This preliminary action reduces the need for frequent recalibration during normal operation, maintaining communication quality while minimizing time loss
Solution Approach 2:
Instead of continuous calibration, the system implements periodic calibration at predetermined intervals or under specific conditions (e.g., when communication quality degradation is detected). This approach maintains reliable communication while minimizing the time spent on calibration operations by calibrating only when necessary
Data Source
AI summary
An embodiment of the invention provides an electronic device. The electronic device includes a digital-to-analog converter (DAC), a transmitter front-end (TX FE), an amplifier, an analog-to-digital converter (ADC), and a swap circuitry. The TX FE has a first and a second input end coupled to a first and a second output end of the DAC, respectively. The ADC has a first and a second input end coupled to a first and a second output end of the amplifier, respectively. The swap circuitry is configured to couple the first and second output ends of the DAC to a first and a second input end of the amplifier in a normal state, respectively, and couple the first and second output ends of the DAC to the second and first input ends of the amplifier in a swapped state, respectively.