Mobile Terminal Transmitter Phase Control for Harmonic Rejection
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Solution Overview
Problem
Mobile terminals face increased harmonic distortion issues due to the integration of multimode/multiband communication systems, which degrades communication system performance and restricts operation to specific frequency bands, necessitating improved harmonic elimination structures for linearity and signal-to-noise ratio (SNR) enhancement.
Innovation Solution
A mobile terminal with a transmitting part that includes multiple baseband units and up-converters, controlled by a controller to operate in harmonic rejection, first non-harmonic rejection, and second non-harmonic rejection modes, adjusting signal phases to improve harmonic distortion, SNR, and linearity characteristics, and utilizing power amplifiers and combiners to manage distortion signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a higher division ratio is used in the up-converter to achieve harmonic rejection, then harmonic distortion characteristics are improved, but the system is restricted to specific frequency bands
Solution Approach 1:
The transmitting part is divided into multiple up-converters (first up-converter and second up-converter) with different division ratios. Each up-converter handles specific frequency bands optimized for its division ratio, allowing the system to achieve harmonic rejection in each segment while covering a broader overall frequency range. This segmentation resolves the contradiction by eliminating the need to use a single high division ratio across all bands.
Solution Approach 2:
The system dynamically selects which up-converter to use based on the operating frequency band. The controller activates the first up-converter for bands where its division ratio provides optimal harmonic rejection, and switches to the second up-converter for other bands. This dynamic adaptation allows the system to maintain good harmonic characteristics across multiple frequency bands without being restricted to a specific band.
2Productivity
If multiple power amplifiers are used to maintain high output power, then productivity is improved, but harmonic distortion increases
Solution Approach 1:
The power amplification function is segmented across multiple up-converters, each with its own power amplifier. By distributing the total output power requirement across multiple amplifiers operating at different stages, the system maintains high overall output power while each individual amplifier operates at lower power levels where harmonic distortion is reduced. The segmented architecture prevents the harmonic accumulation that would occur with a single high-power amplifier.
Solution Approach 2:
The patent converts the potentially harmful effect of multiple amplifiers (which would normally increase harmonic distortion) into a benefit by using the multiple up-converter stages to progressively build up the signal. Each stage contributes to the final high output power while the different division ratios and phase relationships between stages cause harmonic components to cancel out, transforming what would be a harmful multipliers effect into a beneficial harmonic rejection mechanism.
3Reliability
If a harmonic elimination structure is used to improve linearity, then signal quality is improved, but device complexity increases
Solution Approach 1:
The multiple up-converters serve multiple functions simultaneously: they perform frequency conversion, provide harmonic rejection through different division ratios, enable dynamic band selection, and distribute power amplification. This multi-functionality means that while the structure appears more complex, each component performs several critical functions that would otherwise require separate dedicated circuits, effectively managing the complexity burden.
Solution Approach 2:
The system changes the division ratio parameter of the up-converters to achieve harmonic rejection. By adjusting this key parameter (using first up-converter with first division ratio and second up-converter with second division ratio), the system achieves improved linearity and harmonic characteristics without requiring fundamentally different or much more complex circuit architectures. The parameter-based approach allows for relatively simple implementation compared to more aggressive harmonic elimination techniques.
Data Source
AI summary
A mobile terminal performing harmonic rejection includes a plurality of baseband units generating a baseband signal; a plurality of up-converters converting the baseband signal into a radio frequency (RF) signal; and a controller controlling phases of a plurality of signals applied to the plurality of baseband units and the plurality of up-converters. Meanwhile, the controller may perform at least one of a harmonic rejection mode, a first non-harmonic rejection mode for improving a signal-to-noise ratio (SNR), and a second non-harmonic rejection mode for improving linearity to provide a transmitting part having improved harmonic distortion characteristics and the mobile terminal having the transmitting part.