Mixer IM2 Compensation Using Automatic Control Value Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RF receiver architectures, such as direct-conversion receivers, suffer from component mismatches that lead to DC offsets and reduced dynamic range due to limited headroom in variable gain amplifiers, which cannot be adaptively compensated post-manufacture or for external bandpass filtering circuit mismatches.
Innovation Solution
An automatic compensation system that includes a mixer, a detector, and a compensation determination circuit to select the optimal mixer-control signal values, reducing second-order intermodulation distortion by dynamically adjusting impedance and local oscillator parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual fuse array configuration is used to compensate for component mismatches, then DC offset compensation is achieved, but the process is time-consuming and cannot compensate for external bandpass filtering circuit mismatches
Solution Approach 1:
The system uses an automatic compensation mechanism where the receiver itself performs the compensation process. A detector measures the DC offset, and a compensation determination circuit automatically adjusts the impedance of the bandpass filtering circuit based on the measured offset, eliminating the need for manual technician intervention and fuse array configuration.
Solution Approach 2:
The system implements a feedback loop where the detector continuously monitors the DC offset in the baseband signal and feeds this information back to the compensation determination circuit, which then adjusts the impedance accordingly. This closed-loop feedback mechanism enables continuous automatic compensation without manual intervention.
2Manufacturing precision
If fixed compensation is applied during manufacture, then initial mismatch compensation is achieved, but adaptability to component aging and environmental changes is lost
Solution Approach 1:
The system transitions from static fixed compensation to dynamic adaptive compensation. The impedance of the bandpass filtering circuit is made adjustable and can be dynamically changed based on real-time DC offset measurements, allowing the system to adapt to component aging, temperature changes, and other environmental variations throughout the product lifecycle.
Solution Approach 2:
The system performs preliminary compensation by pre-configuring adjustable impedance elements in the bandpass filtering circuit, which are then automatically tuned during operation based on measured DC offsets, combining the benefits of pre-planned compensation with adaptive adjustment.
3Reliability
If external bandpass filtering circuits are used to improve selectivity, then filtering performance is enhanced, but component mismatches and DC offsets increase
Solution Approach 1:
The system introduces an intermediary compensation mechanism between the external bandpass filtering circuit and the baseband processing. The compensation determination circuit acts as a mediator that measures the DC offset generated by the filtering circuit and adjusts the impedance to compensate for the mismatches, allowing the external filter to be used without its harmful effects.
Solution Approach 2:
The system converts the harmful DC offset and mismatch effects into useful information by measuring them with the detector. The measured offset values are then used to adjust the impedance in a way that compensates for the original harmful effects, effectively turning the problem into a solution.
Data Source
AI summary
An apparatus, for automatically selecting a compensation value usable to reduce a second order intermodulation (IM2) product in an output signal of a mixer, may include: a mixer to output a mixed signal; a detector to detect an product in samples corresponding to the mixed signal; a compensation determination circuit to do the following automatically, to apply a plurality of candidate values of a mixer-control signal to the mixer, the mixer-control signal affecting a magnitude of an IM2 product in the mixed signal, to evaluate samples from the detector corresponding to the plurality, respectively, and to select one among the plurality candidate values as the compensation value.