Balanced Single-Ended Doherty Amplifier for VSWR-Resilient QAM
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Solution Overview
Problem
Designing radio-frequency amplifiers for electronic devices that maintain high output power efficiency and performance across different wireless signal modulation schemes, such as QPSK and QAM, is challenging due to variations in voltage standing wave ratio (VSWR) angles, which degrade performance for 64/256-QAM signals.
Innovation Solution
Implementing a balanced Doherty amplifier circuitry with two parallel Doherty amplifiers coupled in a balanced fashion, using single-ended amplifiers with overlapping shunt inductors and transformer-based couplers for signal splitting and impedance matching, to achieve high efficiency and resilience across various digital signal modulation schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single amplifier path is used, then the device complexity is low, but the output power efficiency and performance across different modulation schemes deteriorates
Solution Approach 1:
The amplifier is divided into two separate amplifier paths (first and second amplifier paths), each capable of processing signals independently. This segmentation allows each path to be optimized for specific modulation schemes, improving overall adaptability while managing complexity through modular design
Solution Approach 2:
The balanced amplifier configuration with splitter and combiner circuits enables the system to handle multiple modulation schemes (QPSK, QAM, etc.) universally through a single integrated structure. The circuit can adapt to different modulation types without requiring separate dedicated amplifiers for each scheme
2Use of energy by moving object
If high output power efficiency is prioritized, then the efficiency improves, but the voltage standing wave ratio (VSWR) performance deteriorates
Solution Approach 1:
The amplifier paths are designed with asymmetric characteristics where each path can have different impedance matching networks and amplifier configurations optimized for specific operating conditions. This asymmetry allows one path to optimize for efficiency while the other compensates for VSWR variations, achieving both goals simultaneously
Solution Approach 2:
The circuit employs adjustable impedance matching parameters through variable capacitors and inductors in the input and output matching networks. These parameters can be tuned to optimize the balance between output power efficiency and VSWR performance based on the specific modulation scheme and operating conditions
3Productivity
If traditional amplifier design is used, then the design process is simple, but it cannot maintain high efficiency for both QPSK and 64/256-QAM signals
Solution Approach 1:
The amplifier incorporates dynamic biasing control and adjustable impedance matching that can adapt in real-time to different modulation schemes. The circuit dynamically reconfigures its operating parameters to maintain high efficiency whether transmitting QPSK or 64/256-QAM signals, rather than being fixed for a single mode
Solution Approach 2:
The splitter and combiner circuits act as intermediaries that distribute and recombine signals between the two amplifier paths. This intermediary structure enables the system to achieve high efficiency for multiple modulation schemes by intelligently routing signals through appropriate amplifier paths while maintaining overall system coherence
Data Source
AI summary
Amplifier circuitry is provided that includes a splitter circuit, a combiner circuit, a first amplifier path coupled between the splitter circuit and the combiner circuit, and a second amplifier path coupled between the splitter circuit and the combiner circuit. The first amplifier path can include a first amplifier of a first type and a second amplifier of a second type different than the first type. The second amplifier path can include a third amplifier of the first type and a fourth amplifier of the second type. The first, second, third, and fourth amplifiers can be single-ended amplifiers with shunt inductors coupled at their outputs. The shunt inductors associated with the first and second amplifiers can be partially overlapped to save area. The shunt inductors associated with the third and fourth amplifiers can be partially overlapped to save area.