Reconfigurable Doherty Output Circuit 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 the load modulation associated with high power regions does not hold, leading to inefficient signal amplification when average output power levels decrease significantly below the backed-off efficiency peak.
Innovation Solution
Implementing a reconfigurable Doherty power amplifier with a dynamically adjustable output circuit that can switch between multiple states based on traffic loading or anticipated conditions, allowing optimal impedance matching across a wide range of average output power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional Doherty power amplifier operates at reduced average output power levels significantly below PBO, then the amplifier can handle low power signals, but operational efficiency decreases rapidly
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 in real-time, maintaining high efficiency across both high and low power regions by selecting the appropriate circuit configuration for the current operating conditions
Solution Approach 2:
The invention changes the impedance parameters of the output circuit by switching between different configurations. This parameter change enables the amplifier to maintain optimal load modulation conditions at different power levels, specifically allowing high efficiency operation at reduced average output power levels below PBO by adjusting the output circuit to a state suitable for low power operation
2Loss of energy
If a reconfigurable output circuit is implemented to maintain high efficiency across wide power ranges, then operational efficiency improves at reduced power levels, but device complexity increases
Solution Approach 1:
The output circuit is segmented into multiple configurable states or modes, each optimized for specific power level ranges. This segmentation allows the complex reconfiguration capability to be broken down into discrete, manageable states that can be selectively activated based on operating conditions, making the overall system complexity more controllable while still achieving wide-range efficiency
Data Source
AI summary
A Doherty power amplifier includes a first amplifier with a first output capacitance, a second amplifier with a second output capacitance, a reconfigurable impedance inverter, and a variable output impedance transformer. The reconfigurable impedance inverter includes a combining node and first, second, and third variable networks. The first variable network and the first amplifier output capacitance establish a first amplifier effective output capacitance that is less than the first output capacitance. The second variable network provides a series inductance between the first amplifier output and the combining node. The third variable network and the second amplifier output capacitance establish a second amplifier effective output capacitance that is less than the second output capacitance. The output impedance transformer includes a fourth variable network that establishes a combining node impedance. The first, second, and third variable networks and the output impedance transformer may be reconfigured based on traffic loading conditions.