Asymmetrical Doherty Amplifier Phase Layout for Oscillation Control
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Solution Overview
Problem
High frequency amplifiers face challenges in heat dissipation and stability due to close proximity of driver and peak amplifiers, leading to potential electrical instability and oscillation, especially in three-dimensional mounting configurations.
Innovation Solution
The design incorporates an asymmetrical Doherty amplifier with a phase adjusting circuit that sets the electrical length between the driver and peak amplifier terminals to achieve antiphase signals, along with a base member for heat dissipation, and a grounded metal layer to shield electromagnetic interference, ensuring stable operation and efficient heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If three-dimensional mounting method is used to miniaturize the amplifier, then the mounting space is reduced, but heat dissipation becomes difficult due to close proximity of components
Solution Approach 1:
The patent transitions from planar mounting to three-dimensional stacked mounting, where the first circuit board with amplifiers is positioned above the second circuit board with passive components, utilizing vertical space to reduce footprint while maintaining thermal management capabilities through strategic component placement and spacing
Solution Approach 2:
The patent applies different thermal management strategies to different regions: the base member provides heat dissipation for power amplifiers, while the stacked configuration allows heat paths to be optimized locally for each component based on its thermal requirements and proximity to heat sinks
2Volume of moving object
If driver amplifier and peak amplifier are mounted close together, then the device size is reduced, but electrical stability deteriorates due to potential oscillation
Solution Approach 1:
The patent introduces a ground layer as an intermediary between the driver amplifier and peak amplifier, providing electromagnetic shielding and signal reference that prevents oscillation while allowing close mounting. The ground layer acts as a barrier that maintains electrical stability despite reduced spacing
Solution Approach 2:
The patent extracts the ground shielding function into a separate dedicated layer between the amplifiers, rather than relying on proximity alone, to actively prevent electromagnetic interference and maintain stability in the compact three-dimensional configuration
3Use of energy by moving object
If asymmetrical Doherty amplifier configuration is used, then power efficiency is improved, but circuit complexity increases due to additional components
Solution Approach 1:
The patent divides the amplifier system into distinct functional modules: driver amplifier, carrier amplifier, and peak amplifier, each with specific functions. This segmentation allows the asymmetrical Doherty configuration to achieve high power efficiency through selective operation while organizing complexity into manageable, independently optimized units
Solution Approach 2:
The patent designs the circuit boards and base members to serve multiple functions: electrical connection, mechanical support, thermal management, and electromagnetic shielding. This multi-functionality reduces overall system complexity by consolidating functions into fewer components despite the complex amplifier architecture
Data Source
AI summary
A high frequency amplifier includes an asymmetrical Doherty amplifier having a carrier amplifier, a peak amplifier, a branch circuit, and a phase adjusting circuit, a driver amplifier, and a base member mounting a first circuit board mounting the driver amplifier, the carrier amplifier, and the peak amplifier and a second circuit board mounting the circuits. The branch circuit divides a path of a RF signal into input paths of the peak and carrier amplifiers. The driver amplifier, the carrier amplifier, and the peak amplifier have rear surfaces in contact with the base member. The electrical length from the output terminal of the driver amplifier to the input terminal of the peak amplifier, when converted based on a phase of the signal, is from (2n+1)×π−π/4 to (2n+1)×π+π/4, where n is an integer greater than or equal to zero.