BAW Resonator Recombining Filter for Efficient Outphasing Amplifiers
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Solution Overview
Problem
Current amplifier modules for mobile communication devices face challenges in achieving low power consumption while maintaining amplification quality, especially when dealing with signals of non-constant amplitude, and require compact and efficient recombining stages to minimize interference and distortion.
Innovation Solution
The use of bulk-acoustic wave coupled-resonator filters (BAW-CRF) in the recombining stage of outphasing amplifiers, which are compact, efficient, and suitable for mobile equipment, allowing for the recombination of amplified signals with minimal distortion and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If linear amplifiers are used to amplify signals with non-constant amplitude, then signal distortion is avoided, but power consumption increases
Solution Approach 1:
The signal is segmented into in-phase (I) and quadrature (Q) components, which are then processed separately through constant-envelope modulation. This allows the use of efficient non-linear amplifiers for each component while maintaining the original signal's amplitude information through phase relationships, thus reducing power consumption without significant distortion
Solution Approach 2:
An intermediary constant-envelope signal is introduced through the outphasing technique. The original variable-envelope signal is converted to two constant-envelope signals with varying phase difference, which can be amplified efficiently by non-linear amplifiers, and then recombined to recover the original signal characteristics
2Use of energy by moving object
If non-linear amplifiers are used to reduce power consumption, then energy efficiency improves, but signal distortion increases for variable amplitude signals
Solution Approach 1:
The signal parameters are transformed from amplitude modulation to phase modulation. By converting the variable-envelope signal into two constant-envelope signals with varying phase difference (outphasing), the signal can be amplified by non-linear amplifiers without distortion, as the amplitude information is encoded in the phase relationship rather than the envelope
3Loss of information
If traditional passive components (transformers, quarter wavelength lines, magnetic couplers) are used for signal recombining, then outphasing amplification is achieved, but device dimensions increase and efficiency decreases
Solution Approach 1:
Traditional mechanical/passive electromagnetic components (transformers, transmission lines, magnetic couplers) are replaced with an integrated active recombining circuit implemented using transistor-based active devices. This substitution enables compact integration while maintaining the outphasing signal recombination function, significantly reducing device volume and improving efficiency
4Loss of information
If traditional passive components are used for signal recombining, then signal recombination is achieved, but efficiency performance deteriorates
Solution Approach 1:
Passive electromagnetic components are replaced with an active recombining circuit using transistors, which can actively control the signal combination process. This active approach minimizes energy losses associated with passive component resistance and magnetic losses, thereby improving overall amplifier efficiency while maintaining signal recombination quality
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
BAW-CRF filters enable high energy efficiency in power amplification with low insertion losses, reducing power consumption and interference, while maintaining amplification quality for signals with variable amplitudes, and are suitable for compact integration in mobile devices.
Implementation Method 1
the recombining stage includes an assembly of bulk-acoustic wave resonators coupled to each other
Implementation Method 2
BAW-CRF filters consist of a stack of several bulk acoustic wave resonators which are coupled by an assembly of acoustically passive layers
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A power amplifier filter for radio-frequency signals having an outphasing type architecture comprising a first stage (2) capable of generating, from an input signal s(t), two signals S1(t), S2(t) having an identical amplitude but phase shifted relative to each other, a second amplifier stage (3) for said signals S1(t), S2(t), and a third recombining stage (4) capable of summing the two signals s'1(t), s'2(t) obtained from second stage (3), characterized in that recombining stage (4) includes an assembly of acoustic wave resonators coupled to each other, some of these resonators referred to as 'input resonators' being connected to the outputs of second stage (4) and others of these resonators referred to as 'output resonators' being connected to the output terminals of the filter.