Multimode RF Transmitter With Impedance Controller
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Solution Overview
Problem
Current communication transmitters using RF digital-to-analog converters (DACs) are limited to narrow bands and specific communication systems, leading to degraded performance in other frequency bands, making them inefficient for supporting multiple communication services like 2G, 3G, LTE, and WiBro.
Innovation Solution
A transmitter design that employs multiple RF DACs with an impedance controller to adjust frequency ranges by using capacitive power combiners and look-up tables to store pre-calculated impedance values, allowing the transmitter to operate in both data transmission and impedance matching modes across different frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single RF DAC is optimized for a predetermined frequency band, then performance in that specific band is improved, but performance in other frequency bands is degraded
Solution Approach 1:
The transmitter is divided into multiple RF DACs, each optimized for a specific frequency band. The system segments the frequency spectrum into multiple bands and assigns dedicated DACs to each band, allowing simultaneous optimization for multiple bands without compromise
Solution Approach 2:
The transmitter achieves multi-functionality by incorporating multiple RF DACs that can operate across different frequency bands. Each DAC serves multiple purposes: it can transmit in its optimized band and also provide impedance matching for other bands, making the system universally applicable across multiple frequency ranges
2Adaptability or versatility
If multiple RF DACs are used to support multiple frequency bands, then frequency band coverage is improved, but device complexity increases
Solution Approach 1:
The system merges the functions of multiple RF DACs with impedance matching circuits into a unified architecture. The capacitive power combiners serve dual purposes: combining power from multiple DACs and providing impedance matching, thereby reducing the need for separate matching circuits and simplifying the overall device structure
Solution Approach 2:
The RF DACs perform self-service by automatically switching between transmission mode and impedance matching mode based on the operating frequency band. The system self-regulates which DAC transmits and which provides impedance matching, eliminating the need for complex external control circuits
3Reliability
If separate impedance matching circuits are added for each frequency band, then impedance matching performance is improved, but device complexity and cost increase
Solution Approach 1:
The capacitive power combiners are designed to perform multiple functions simultaneously: they combine power from multiple RF DACs and provide impedance matching for different frequency bands. This multi-functional design eliminates the need for separate impedance matching circuits for each band, reducing device complexity while maintaining matching performance
Solution Approach 2:
The impedance matching function is merged into the power combining circuitry. The capacitive combiners serve as both power aggregation points and impedance matching elements, consolidating what would traditionally be separate functions into a single integrated structure
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
Enables efficient and adaptive operation across multiple frequency bands, maintaining optimal impedance and performance for various communication standards like LTE and WCDMA, reducing the need for separate matching circuits and saving costs.
Implementation Method 1
Each of the first RF DAC and the second RF DAC may include capacitors configured to be a capacitive power combiner
Implementation Method 2
an impedance controller configured to adjust impedance of one of the first RF DAC and the second RF DAC operating in an impedance matching mode to adjust a frequency range of another one of the first RF DAC and the second RF DAC operating in a data transmission mode
Data Source
AI summary
A transmitter configured to support a multimode and a multiband, using radio frequency (RF) digital-to-analog converters (DACs), includes a first RF DAC configured to transmit a first signal in a first frequency band, and a second RF DAC configured to transmit a second signal in a second frequency band different from the first frequency band. The transmitter further includes an impedance controller configured to adjust impedance of one of the first RF DAC and the second RF DAC operating in an impedance matching mode to adjust a frequency range of another one of the first RF DAC and the second RF DAC operating in a data transmission mode.