Reconfigurable Doherty Output Circuits for Low-Power Efficiency
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Solution Overview
Problem
Conventional Doherty power amplifiers exhibit low efficiency in the low power region of operation, as load modulation in the high power region does not hold, leading to inefficient signal amplification when average output power levels decrease significantly below PBO.
Innovation Solution
Implementing reconfigurable Doherty power amplifiers with dynamically adjustable output circuits that can switch between multiple states based on traffic loading or temporal conditions, optimizing impedance for efficient operation across a wide range of average output power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional Doherty power amplifier operates in the low power region (below PBO), then the carrier amplifier remains active but efficiency decreases rapidly as average output power decreases, because load modulation from the high power region does not hold
Solution Approach 1:
The patent implements a reconfigurable output circuit that can dynamically switch between multiple impedance states based on the operating power level. This allows the amplifier to adapt its load modulation characteristics to maintain efficiency across different power regions, specifically enabling efficient operation in the low power region where conventional fixed-impedance designs fail
Solution Approach 2:
The patent changes the impedance parameters of the output circuit by switching between different configurations. This parameter change enables the amplifier to optimize its operating point for different power levels, transforming the fixed-impedance limitation into a variable-impedance solution that maintains efficiency across the full power range
2Loss of energy
If a conventional Doherty power amplifier is designed for high efficiency at P SAT and P BO, then these power levels are fixed and cannot be adjusted for different traffic loading conditions
Solution Approach 1:
The reconfigurable output circuit enables dynamic adaptation to different traffic loading conditions by switching between multiple impedance states. This allows the amplifier to optimize efficiency for various operating scenarios including different traffic loads and temporal conditions, rather than being fixed for a single operating point
Solution Approach 2:
The patent creates a universal amplifier design that can handle multiple operating conditions through a single reconfigurable circuit. The output circuit serves multiple functions by switching between different impedance states, enabling the same hardware to optimize efficiency across diverse traffic loading scenarios without requiring multiple dedicated circuits
Data Source
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AI summary
A Doherty power amplifier includes a first amplifier (331) with a first output capacitance (333), a second amplifier (351) with a second output capacitance (353), a reconfigurable impedance inverter, and a variable output impedance transformer (380). The reconfigurable impedance inverter includes a combining node (370) and first (334), second (340), and third (354) variable networks. The first variable network (334) and the first amplifier output capacitance (333) establish a first amplifier effective output capacitance that is less than the first output capacitance (333). The second variable network (340) provides a series inductance between the first amplifier output (332) and the combining node (370). The third variable network (354) and the second amplifier output capacitance (353) establish a second amplifier effective output capacitance that is less than the second output capacitance (353). The output impedance transformer (380) includes a fourth variable network (383, 384) that establishes a combining node impedance.