Sliding-Mode Outphasing Power Amplifier for Broadband Efficiency
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Solution Overview
Problem
Existing Doherty and Chireix power amplifiers are narrow band in operation and have not been fabricated in an integrated form factor, limiting their application space.
Innovation Solution
A dual-input microwave power amplifier exploiting the Doherty-Chireix continuum with a sliding mode operation, utilizing a main and auxiliary branch transmission line connected to a common load, achieving high average efficiency over a large operating frequency in an integrated form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional Doherty or Chireix amplifier architectures are used, then high average efficiency from peak to back-off power levels is achieved, but the bandwidth is narrow
Solution Approach 1:
The patent implements a sliding mode operation where the amplifier dynamically transitions between Doherty and Chireix operating modes across the frequency band. The main and auxiliary branch transmission lines have different electrical lengths that cause the operating point to slide along the Doherty-Chireix continuum, enabling broadband operation while maintaining high efficiency through adaptive mode switching.
Solution Approach 2:
The patent changes the electrical length parameters of the main branch transmission line (TL1) and auxiliary branch transmission line (TL2) to map across a targeted frequency band. By varying these electrical length parameters with frequency, the amplifier achieves broadband operation while maintaining the load modulation behavior necessary for high average efficiency.
2Adaptability or versatility
If discrete implementations of Doherty-Chireix continuum amplifiers are used, then broadband high efficiency is achieved, but integration is limited
Solution Approach 1:
The patent merges the main and auxiliary power amplifier branches into a single integrated MMIC device. Both the main transistor and auxiliary transistor are fabricated on the same semiconductor substrate with integrated transmission lines and combining network, enabling broadband high-efficiency operation while achieving compact integrated form factor suitable for commercial and defense applications.
Solution Approach 2:
The integrated MMIC design provides universal applicability across multiple frequency bands and military standards (MIL-STD-883, MIL-STD-202). The sliding mode architecture enables the single device to serve multiple functions across different operating conditions, replacing multiple discrete components with one universal integrated solution.
Data Source
AI summary
A dual-input microwave power amplifier (PA) with high-efficiency. The PA exploits the continuum of modes between the Doherty and Chireix PA mode of operation to achieve 40% fractional bandwidth while relying on the physical linear dispersion of the transmission lines of the lossless output combiner. A constant output is achieved at peak power over the entire bandwidth. The output backoff varies from 6 dB in the Doherty mode to 8 dB in the Chireix mode. The PA operates over a wider range of frequencies from 1 to 8 GHz. The dual-input PA operates in mixed-mode and thus requires variable input power drives and outphasing angle.