Segmented RF Transmitter Architecture for Wideband Power Efficiency
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Solution Overview
Problem
Current wireless transmitter architectures, such as Cartesian and polar transmitters, face inefficiencies in handling high bandwidth RF signals, with Cartesian transmitters experiencing 3 dB efficiency loss and polar transmitters struggling with wide bandwidth signals, leading to increased power consumption and complexity.
Innovation Solution
A novel transmitter architecture that selects a segment of a constellation diagram with an opening angle less than 90°, calculates coordinates with respect to new axes, and uses LO signals with a phase difference equal to this angle to generate RF signals, reducing power loss and complexity by avoiding the need for CORDIC algorithms and minimizing the number of digital-to-analog converter cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Cartesian transmitter architecture is used to generate RF signals from complex valued symbols, then high bandwidth modulation schemes can be handled, but 3 dB efficiency loss occurs for worst case symbols
Solution Approach 1:
The constellation diagram is divided into multiple segments with different opening angles. By selecting the appropriate segment for each symbol and using different LO phase differences for different segments, the system achieves both high bandwidth handling and improved power efficiency, avoiding the fixed 3 dB loss of Cartesian architecture.
Solution Approach 2:
The system dynamically adjusts the LO phase difference based on the symbol's position in the constellation diagram. By selecting segments with opening angles less than 90° and adjusting LO phase accordingly, the system adapts to different symbol conditions, improving efficiency while maintaining bandwidth capability.
2Loss of energy
If polar transmitter architecture is used to improve area and power consumption, then high efficiency output stage is achieved, but handling RF signals with wide bandwidth becomes problematic
Solution Approach 1:
The constellation diagram is segmented into multiple regions, each handled by a different LO phase configuration. This segmentation allows the system to process wide bandwidth signals efficiently by distributing the processing across multiple optimized paths, avoiding the bandwidth limitation of traditional polar architecture.
Solution Approach 2:
The transmitter architecture is designed to handle both high efficiency requirements and wide bandwidth signals through a unified segmented approach. The same hardware structure can adapt to different bandwidth and efficiency requirements by selecting appropriate segments and LO phase configurations.
3Ease of operation
If LO signals with 90° phase difference are used in Cartesian architecture, then in-phase and quadrature axes are represented, but power loss increases for symbols with equal magnitude components
Solution Approach 1:
The system changes the LO phase difference parameter from the fixed 90° in Cartesian architecture to variable values less than 90°, selected based on the symbol's segment in the constellation diagram. This parameter change reduces power loss while maintaining proper constellation representation.
Data Source
AI summary
An apparatus for generating a radio frequency signal based on a symbol within a constellation diagram is provided. The constellation diagram is spanned by a first axis representing an in-phase component and an orthogonal second axis representing a quadrature component. The apparatus includes a processing unit configured to select a segment of a plurality of segments of the constellation diagram containing the symbol. The segment is delimited by a third axis and a fourth axis each crossing the origin of the constellation diagram and spanning an opening angle of the segment of less than about 90°. The processing unit is further configured to calculate a first coordinate of the symbol with respect to the third axis, and a second coordinate of the symbol with respect to the fourth axis. The apparatus further includes a plurality of digital-to-analog converter cells configured to generate the radio frequency signal using the first coordinate and the second coordinate.