RF Amplifier Circuit Non-Linearity Mitigation via Auxiliary Transmitter
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Solution Overview
Problem
Mobile terminals, particularly those using 5G communication systems, face performance degradation due to nonlinear output signals in adjacent frequency bands, leading to non-linearity issues in RF amplifiers.
Innovation Solution
A mobile terminal design incorporating a main transmitter and an auxiliary transmitter, with a controller to manage distortion by combining amplified signals and adjusting gain, uses a combination of local oscillators and filters to improve linearity, and includes a Digital Pre-Distortion compensator to address non-linearity in amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an amplifier operates in higher frequency bands (5G communication system), then the communication capability is enhanced, but the saturated input power is lower causing nonlinear output signals in adjacent frequency bands
Solution Approach 1:
The patent divides the transmission system into a main transmitter for the first frequency band and an auxiliary transmitter for the second frequency band. The auxiliary transmitter specifically targets adjacent frequency bands to generate cancellation signals that counteract the nonlinear distortion produced by the main transmitter, thereby resolving the contradiction between enhanced communication capability and nonlinear output signals.
Solution Approach 2:
The patent converts the harmful nonlinear distortion signals into useful cancellation signals. By using the auxiliary transmitter to generate signals that mirror the distortion characteristics of the main transmitter, the harmful nonlinear effects are transformed into beneficial cancellation effects that improve overall system linearity.
2Reliability
If a single transmitter is used, then the device complexity is low, but the linearity performance is degraded due to nonlinear output signals
Solution Approach 1:
The transmission system is segmented into a main transmitter and an auxiliary transmitter, each with dedicated amplifiers and signal processing paths. This segmentation allows the auxiliary transmitter to specifically address linearity issues without significantly increasing overall system complexity, as the auxiliary path can share common components like antennas and control units.
Solution Approach 2:
The auxiliary transmitter is designed to serve multiple functions: it transmits actual communication signals in the second frequency band and simultaneously generates cancellation signals to compensate for nonlinear distortion. This multi-functionality reduces the need for separate dedicated cancellation components, thereby limiting the increase in device complexity.
3Reliability
If multiple transmitters are used to improve linearity, then the linearity performance is improved, but the layout area increases
Solution Approach 1:
The patent merges the auxiliary transmitter's signal processing functions with the main transmitter's existing structure. Both transmitters share common components including the antenna system, control unit, and portions of the RF front-end, thereby reducing the additional layout area required by the auxiliary transmitter while maintaining improved linearity performance.
Solution Approach 2:
The auxiliary transmitter is effectively nested within the overall transmission system architecture, utilizing the existing structural framework and shared resources of the main transmitter. This nesting approach minimizes the additional space required, as the auxiliary path integrates with rather than duplicating the main transmission path's physical infrastructure.
Data Source
AI summary
A mobile terminal according to the present invention includes a main transmitter to amplify and transmit a first signal of a first frequency band through a first path and a second path, and an auxiliary transmitter to amplify and transmit a second signal of a second frequency band through a third path. The mobile terminal further includes a controller to control the amplified first signal and the amplified second signal to be combined with each other when the distortion signal is to occur in frequency bands adjacent to the first frequency band due to the amplified first signal, thereby providing a radio frequency (RF) front end and a mobile terminal with improved non-linearity.