Doherty Power Amplifier Phase Advance for λ/4 Output Matching
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Solution Overview
Problem
Conventional Doherty amplifiers face challenges in achieving the optimal phase length of λ/4 due to excessive phase delay introduced by output matching circuitry, leading to increased size and inefficiency, necessitating additional transmission lines to meet circuit length constraints.
Innovation Solution
The implementation of phase advance networks configured as high-pass filters to mitigate phase delays in the amplifier paths, reducing the overall phase length and group delay, allowing for the achievement of λ/4 phase length without additional transmission lines, thereby reducing package size and improving bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional output matching circuitry is used in Doherty amplifiers, then impedance matching is achieved, but excessive phase delay is introduced increasing phase length beyond optimal λ/4
Solution Approach 1:
The patent extracts the phase delay problem from the output matching circuitry by separating the impedance matching function from the phase correction function. Phase advance networks are introduced as distinct components that specifically address the excessive phase delay without interfering with the impedance matching provided by the output matching circuitry.
Solution Approach 2:
The patent applies preliminary anti-action by introducing phase advance networks that pre-compensate for the excessive phase delay before the signal reaches the output. These networks advance the phase of the signal path to counteract the phase delay introduced by the output matching circuitry, thereby achieving the optimal λ/4 phase length.
2Reliability
If additional transmission lines are added to correct phase length, then optimal λ/4 phase length is achieved, but package size increases
Solution Approach 1:
The phase advance networks serve multiple functions simultaneously: they correct the phase delay, maintain the optimal λ/4 phase length, and do so without requiring additional transmission lines that would increase package size. This multi-functionality resolves the contradiction between phase accuracy and compact size.
Solution Approach 2:
The patent changes the electrical parameters of the existing circuit paths by introducing phase advance networks that modify the phase characteristics. Instead of adding physical transmission lines to change the phase length, the networks alter the phase parameter directly through their filtering action, achieving the same effect in a more compact form.
3Reliability
If phase advance networks are implemented, then phase length is reduced to optimal λ/4, but circuit complexity increases
Solution Approach 1:
The phase advance networks act as intermediary components between the output matching circuitry and the final output. These networks mediate the phase relationship by advancing the phase of the signal path, thereby reducing the overall phase length to the optimal λ/4 without requiring complex reconfiguration of the existing circuit.
4Reliability
If output matching circuitry with excessive phase delay is used, then impedance matching is maintained, but bandwidth is reduced
Solution Approach 1:
The phase advance networks introduce dynamic phase correction that adapts to the frequency characteristics of the signal. By advancing the phase in a frequency-dependent manner, the networks maintain impedance matching across a broader frequency range, thereby increasing the bandwidth of the amplifier while preserving the benefits of the output matching circuitry.
Data Source
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AI summary
In various embodiments, a semiconductor package includes a carrier amplifier (506) connected to a first output of a power divider(504), and a first output matching network (514) connected to the carrier amplifier(506) and an output combining node (510). The first output matching network (514) exhibits a phase delay during operation of the carrier amplifier (506). The semiconductor package includes a phase advance network (516) connected to the first output matching network (514). The phase advance network (516) is configured to offset at least a portion of the phase delay of the first output matching network (514). The semiconductor package includes a peaking amplifier (508) connected to a second output of the power divider (504) and the output combining node (510), and a second output matching network (520) connected to the peaking amplifier (508).