Multi-Stage Power Amplifier Biasing for Gain Flatness
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Solution Overview
Problem
Massive MIMO base stations face challenges in achieving high performance while meeting stringent size and power consumption requirements due to the complexity of large numbers of transceivers.
Innovation Solution
A multiple-stage amplifier configuration is implemented, comprising a driver stage amplifier and a final stage amplifier, both receiving a same output DC bias voltage, with significantly different power densities and semiconductor technologies, optimized for efficient power transfer and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple-stage amplifier configuration with different power densities is used, then gain flatness and power transfer are improved, but device complexity increases
Solution Approach 1:
The amplifier is divided into multiple stages (driver stage and final stage) with different power densities and semiconductor technologies. Each stage is optimized independently for its specific function, allowing gain flatness and power transfer to be improved while managing complexity through functional segmentation.
Solution Approach 2:
The multiple-stage configuration serves multiple functions simultaneously: impedance matching between stages, gain optimization across different frequency ranges, and power transfer enhancement. This multi-functionality resolves the contradiction by making the complex structure justify its value through diverse performance benefits.
2Power
If higher power densities are achieved through increased drain voltage, then power output is improved, but size and power consumption requirements become more stringent
Solution Approach 1:
Different stages of the amplifier use different semiconductor technologies optimized for their specific power density requirements. The final stage uses GaN technology for high power density where needed, while the driver stage uses different technology optimized for its lower power requirements, allowing localized optimization of power characteristics.
Solution Approach 2:
The amplifier system combines different semiconductor technologies (GaN and other materials) in a composite multi-stage configuration. This allows the system to achieve high overall power output while managing power consumption through the synergistic combination of different material properties and stage optimizations.
Data Source
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AI summary
A multiple-stage amplifier includes a driver stage transistor characterized by a first power density, and a final stage transistor characterized by a second power density that is larger than the first power density. A first drain bias circuit is coupled to a first drain terminal of the driver stage transistor, and is configured to provide a first drain bias voltage to the first drain terminal. A second drain bias circuit is coupled to a second drain terminal of the final stage transistor, and is configured to provide a second drain bias voltage to the second drain terminal, where the second drain bias voltage equals the first drain bias voltage. An interstage impedance matching circuit is coupled between the first drain terminal and a gate terminal of the final stage transistor. The multiple-stage amplifier may be included in a Doherty power amplifier, a transceiver, and/or a transceiver array.