N-Way Doherty Distributed Amplifier With Power Tracking at Output Back-Off
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Solution Overview
Problem
Conventional N-way Doherty amplifiers face challenges in optimizing gain and efficiency performance at high output back-off power, particularly for high peak-to-average power ratio signals, due to difficulties in device matching and reduced gain leading to increased power dissipation.
Innovation Solution
The implementation of a dual-feed distributed amplifying method replaces conventional power splitters and combiners with hybrid couplers and transmission lines, along with adaptive bias supply techniques like envelope tracking and average power tracking, to enhance gain and efficiency performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional power splitters and combiners are used in N-way Doherty amplifier, then the structure is simple, but the gain is reduced and isolation is poor
Solution Approach 1:
The patent replaces conventional power splitters and combiners with hybrid couplers, which are based on electromagnetic coupling principles rather than simple power division. This substitution improves gain and isolation performance while maintaining reasonable structural complexity through the use of transmission line-based hybrid couplers.
2Device complexity
If fixed bias supply is used in N-way Doherty amplifier, then the circuit is simple, but efficiency at high output back-off power is poor
Solution Approach 1:
The patent implements adaptive bias supply techniques where the bias voltages are dynamically adjusted based on the input signal envelope. This dynamic adaptation allows the amplifier to maintain optimal efficiency across varying output power levels, particularly improving performance at high output back-off conditions while managing circuit complexity through controlled adaptation mechanisms.
3Loss of energy
If conventional N-way Doherty amplifier is used, then efficiency at high output back-off power is improved, but gain is reduced and power dissipation increases
Solution Approach 1:
The patent replaces conventional power splitters and combiners with hybrid couplers to improve gain performance while maintaining the efficiency benefits of the N-way Doherty structure. The hybrid coupler-based implementation reduces the gain loss typically associated with conventional power division networks.
4Loss of energy
If asymmetric Doherty amplifier with different power device sizes is used, then efficiency at various back-off powers is improved, but optimization of gain and output power becomes difficult
Solution Approach 1:
The patent employs adaptive bias supply techniques that dynamically adjust operating parameters to optimize performance. This approach allows the amplifier to achieve efficient operation at various back-off powers while using identical power devices, thereby avoiding the complex matching requirements of asymmetric designs with different device sizes.
Data Source
AI summary
A power amplifier using N-way Doherty structure with adaptive bias supply power tracking for extending the efficiency region over the high peak-to-average power ratio of the multiplexing modulated signals such as wideband code division multiple access and orthogonal frequency division multiplexing is disclosed. In an embodiment, present invention uses a dual-feed distributed structure to an N-way Doherty amplifier to improve the isolation between at least one main amplifier and at least one peaking amplifier and, and also to improve both gain and efficiency performance at high output back-off power. Hybrid couplers can be used at either or both of the input and output. In at least some implementations, circuit space is also conserved due to the integration of amplification, power splitting and combining.