RF DAC Multiband Transmitter Using Filtered Nyquist Images
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Solution Overview
Problem
Conventional multiband transmitter architectures require duplicate signal processing paths and multiple local oscillators, leading to increased component count, reliability issues, spurious emissions, and synchronization challenges, which increase costs and power consumption.
Innovation Solution
A frequency agile multiband transmitter using a radio frequency digital-to-analog converter that generates and filters carrier signals, allowing for concurrent operation across multiple frequency bands by utilizing numerically controlled oscillators and a filter to select image signals within the Nyquist bands, reducing the need for RF modulators and mixers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional multiband transmitter architectures use several radio paths and combine paths at RF, then multiple frequency bands can be covered, but the component count increases and reliability decreases
Solution Approach 1:
The patent merges multiple radio paths into a single RF path by using a single local oscillator and combining baseband signals digitally before RF conversion. This reduces the number of components while maintaining multiband coverage capability through software-defined radio architecture.
Solution Approach 2:
The single RF path and local oscillator are designed to handle multiple frequency bands universally through software configuration. The baseband processing stage can generate signals for different bands, and the RF path processes all bands through a unified architecture, making the system multi-functional without requiring duplicate hardware paths.
2Adaptability or versatility
If conventional multiband architectures use duplicate signal processing paths, then multiple frequency bands can be supported, but hardware costs and power consumption increase
Solution Approach 1:
The patent combines multiple signal processing functions into a single unified path. Instead of having separate processing chains for each frequency band, the system uses one RF path and one local oscillator that can be software-configured to operate across multiple bands, significantly reducing power consumption by eliminating redundant hardware operation.
Solution Approach 2:
The baseband processor and RF path are designed as universal components that can handle multiple frequency bands through software reconfiguration. This multi-functionality allows the same hardware to serve multiple purposes across different bands without requiring duplicate dedicated hardware for each band, thereby reducing overall power consumption.
3Adaptability or versatility
If multiple local oscillators are used in multiband transmitters, then different frequency bands can be generated, but spurious emissions increase and synchronization becomes complex
Solution Approach 1:
The patent uses a single local oscillator instead of multiple oscillators to generate all required frequency bands. This consolidation eliminates the spurious emissions that would arise from multiple oscillators and removes the need for complex synchronization between them. The single oscillator's output is processed through software-defined radio techniques to generate the necessary frequency translations for multiple bands.
Solution Approach 2:
The patent introduces baseband signal processing as an intermediary stage between the single local oscillator and the RF output. This baseband processing stage performs digital signal manipulation that enables a single oscillator to effectively generate multiple frequency bands through mathematical modulation techniques, avoiding the need for multiple physical oscillators and their associated spurious emissions.
4Adaptability or versatility
If conventional multiband transmitters use independent data captures with various group delays, then different frequency bands can be processed, but phase synchronization becomes difficult
Solution Approach 1:
The patent merges the processing of multiple frequency bands into a single unified signal path at the baseband level. By combining the baseband signals before RF conversion, the system processes all bands through a common pathway, which naturally maintains phase coherence and eliminates the synchronization complexity that would arise from independent processing paths with different group delays.
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 approach simplifies radio board design, lowers power consumption, improves reliability, and reduces component count, while enabling flexible and reconfigurable operation across multiple frequency bands.
Implementation Method 1
a radio frequency digital-to-analog converter operating at a sampling frequency. The output of the radio frequency digital-to-analog converter includes a first carrier signal corresponding to the first radio frequency digital signal and having a first frequency below the sampling frequency and an image of the first carrier signal having a second frequency above the sampling frequency
Implementation Method 2
The output of the radio frequency digital-to-analog converter is filtered to select the image of the first carrier signal for transmission
Data Source
AI summary
Embodiments of the claimed subject matter provide a method and apparatus for generating a first radio frequency digital signal and providing the first radio frequency digital signal to a radio frequency digital-to-analog converter operating at a sampling frequency. The output of the radio frequency digital-to-analog converter includes a first carrier signal corresponding to the first radio frequency digital signal and having a first frequency below the sampling frequency and an image of the first carrier signal having a second frequency above the sampling frequency. The output of the radio frequency digital-to-analog converter is filtered to select the image of the first carrier signal for transmission.