DC Offset Calibration in RF Transceiver Baseband
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RF transceiver systems face challenges in correcting DC offsets, which degrade error vector magnitude (EVM) and carrier suppression performance due to circuit mismatches and process variations, often requiring complex additional circuitry for calibration.
Innovation Solution
A closed-loop DC offset calibration technique is employed, utilizing a feedback path to determine and compensate for DC offsets in the transmit path, with the receive path used as both feedback and receive paths to reduce complexity and cost, and dynamically adjust for changes in gain settings without re-running the correction loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DC offset correction techniques are used, then DC offset performance is improved, but device complexity increases
Solution Approach 1:
The patent combines the DC offset correction function with the existing receive path by using the receive path as a feedback path. The receive path processes the transmitted signal and feeds it back to measure DC offsets, which are then used to correct the transmit baseband signal. This merging eliminates the need for separate correction circuitry while achieving effective DC offset compensation.
Solution Approach 2:
The system uses its own receive path to measure and correct DC offsets in the transmit path. The receive path naturally processes the transmitted signal and can extract DC offset information, which is then fed back to adjust the transmit baseband signal. This self-service approach eliminates the need for external or additional correction mechanisms.
2Measurement precision
If additional correction circuitry is added, then DC offset performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the DC offset correction functionality into the existing receive path, eliminating the need for additional correction circuitry. By reusing existing components (receive path as feedback path, baseband processing units), the solution reduces component count and manufacturing complexity while maintaining effective DC offset correction performance.
3Measurement precision
If closed-loop feedback calibration is implemented, then DC offset correction accuracy is improved, but system complexity increases
Solution Approach 1:
The patent implements a closed-loop feedback calibration system where the receive path processes the transmitted signal and feeds back DC offset measurements to the baseband processing unit. The baseband processing unit uses this feedback to dynamically adjust and correct DC offsets in the transmit baseband signal, achieving accurate correction through continuous feedback without requiring complex external calibration equipment.
Solution Approach 2:
The receive path serves multiple functions: it acts as both the receive path for incoming signals and the feedback path for DC offset measurement. This multi-functionality reduces the need for dedicated calibration circuitry while maintaining accurate closed-loop correction capability.
4Measurement precision
If DC offset correction is performed, then signal quality is improved, but power consumption increases
Solution Approach 1:
The system uses its existing receive path and baseband processing units to perform DC offset correction without requiring additional dedicated correction circuitry. By reusing existing components that would be active during normal operation anyway, the solution minimizes additional power consumption while achieving improved signal quality through effective DC offset compensation.
Data Source
AI summary
A radio frequency (RF) transceiver is provided. The RF transceiver comprises a transmit path comprising an output coupled to an RF antenna, a feedback path comprising an input coupled to the output of the transmit path, and a DC offset calibration module comprising a first input coupled to an output of the feedback path, a second input to receive a first signal and an output connected to an input of the transmit path. The DC offset calibration module is operable to determine a first direct current (DC) offset of a closed-loop path comprising the transmit path and the feedback path and determine a second DC offset based on the feedback path exclusive of the transmit path.