Polar Transmitter Power Path Filtering for Variable-Bandwidth Uplinks
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Solution Overview
Problem
In radio transmitters, noise induced by components in the power supply signal path causes spurious emissions, leading to interference between adjacent frequency resource blocks and reduced system capacity, especially in modern wireless telecommunication systems with variable-bandwidth transmissions.
Innovation Solution
A polar transmitter structure is implemented with a low-pass filter having adjustable parameters to suppress spurious signal components, and a switched-mode power supply unit that follows the amplitude levels of the transmission signal to reduce noise power, along with predistortion units to compensate for distortion caused by the power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a power amplifier is used to amplify the transmission signal to a high level, then the signal quality is improved, but noise induced by components in the power supply signal path increases causing spurious emissions
Solution Approach 1:
The transmission signal is separated into amplitude component and phase component. The amplitude component modulates the power supply signal while the phase component is up-converted and applied to the power amplifier input, isolating the noise generation path from the signal path
Solution Approach 2:
A low-pass filter is introduced as an intermediary component in the power supply signal path to suppress noise and spurious emissions generated by power amplifier components, allowing the power amplifier to operate at high levels without introducing excessive interference
2Object-generated harmful factors
If noise power in the power supply signal is reduced to minimize spurious emissions, then adjacent-channel interference is decreased, but the complexity of the power supply signal path increases
Solution Approach 1:
The low-pass filter is integrated into the power supply signal path of the polar transmitter, combining noise suppression functionality with the existing power supply architecture. This merging approach reduces adjacent-channel interference while minimizing additional complexity by utilizing the existing signal path infrastructure
3Productivity
If a low-pass filter with adjustable parameters is used to suppress spurious signal components, then system capacity is improved, but the device complexity increases
Solution Approach 1:
The low-pass filter is designed with adjustable parameters that can be dynamically configured based on transmission requirements. This dynamic adaptability allows the filter to optimize system capacity for different operating conditions while the adjustability is managed through control circuitry that minimizes user-facing complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the quality of uplink communications and increases the capacity of the system by reducing adjacent-channel leakage and noise-induced interference, enhancing the overall performance of the radio transmitter.
Implementation Method 1
A polar transmitter structure is implemented with a low-pass filter having adjustable parameters to suppress spurious signal components
Implementation Method 2
a switched-mode power supply unit that follows the amplitude levels of the transmission signal to reduce noise power
Implementation Method 3
a transmission signal, i.e. the signal being transmitted, is amplified in a radio frequency power amplifier which amplifies the transmission signal to a level suitable for transmission
Data Source
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AI summary
This document discloses a solution for processing a transmission signal in a radio transmitter. According to an aspect, an apparatus comprises: means for obtaining an amplitude component of a transmission signal including transmission symbols distributed to a number of transmission resource blocks allocated to a radio transmitter for transmission; low-pass filtering means for low-pass filtering the amplitude component; means for adjusting a bandwidth of a pass band of the low-pass filtering means according to the number of transmission resource blocks; and power supply means for receiving the low-pass filtered amplitude component as an input and for generating a power supply signal for a power amplifier from the low-pass filtered amplitude component.