Monolithic Doherty Amplifier Phase Shifter Integration
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Solution Overview
Problem
Conventional Doherty power amplifiers face challenges in supporting broad bandwidths for 5G deployments due to placement tolerances, wirebond variations, and structural variations on printed circuit boards, leading to inconsistent RF performance and difficulty in meeting stringent linearity, efficiency, and power gain requirements.
Innovation Solution
A monolithic Doherty power amplifier with integrated main and peaking power transistors, a phase shifter/impedance inverter, and a signal combiner on a single semiconductor die, which reduces device-to-device variation and wirebond length/height variations, ensuring consistent RF performance by closely coupling the signal combiner to the peaking transistor's drain terminal and using a simulated quarter wave transmission line with a CLC topology for phase difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional Doherty PA configurations are used with separate main and peaking amplifier modules on printed circuit boards, then the amplifier can be assembled using discrete components, but placement tolerances and wirebond variations lead to inconsistent RF performance
Solution Approach 1:
The patent integrates the main amplifier, peaking amplifier, phase shifter, and combiner into a single monolithic semiconductor device. This merging eliminates the need for separate modules on printed circuit boards, removing the sources of variation (placement tolerances, wirebond variations) that caused inconsistent RF performance while maintaining manufacturability through standard semiconductor fabrication processes
2Ease of manufacture
If discrete main and peaking power amplifier modules are used with wirebonds, then the device can be constructed using standard packaging, but wirebond length and height variations cause device-to-device inconsistency
Solution Approach 1:
By integrating all amplifier components and interconnections into a single monolithic semiconductor device, the patent eliminates wirebonds entirely. The internal semiconductor interconnections provide consistent electrical paths without the length and height variations inherent in wirebond packaging, thereby improving device-to-device consistency while remaining compatible with standard semiconductor packaging processes
3Device complexity
If conventional PCB-based Doherty amplifier structures are used, then the amplifier can be implemented with separate circuit boards, but structural variations lead to inconsistent RF performance
Solution Approach 1:
The patent consolidates the main amplifier, peaking amplifier, phase shifter, and combiner into a single monolithic integrated circuit, eliminating the need for separate PCB modules and their associated structural variations. This integration ensures uniform RF performance across all devices while maintaining functional modularity through the internal architecture of the integrated circuit
Solution Approach 2:
Instead of assembling discrete amplifier modules onto a PCB and connecting them with wirebonds (conventional approach), the patent inverts the manufacturing sequence by fabricating the entire amplifier as a single integrated semiconductor device using standard IC processes, thereby eliminating the sources of variation inherent in modular assembly
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the production of Doherty amplifiers with improved consistency in RF performance, reducing production variations and enhancing efficiency and linearity, thus meeting the demanding requirements of 5G infrastructure.
Implementation Method 1
a simulated quarter wave transmission line with a CLC topology may be used to introduce a 90-degree phase difference
Data Source
AI summary
A multiple-path amplifier (e.g., a Doherty amplifier) includes a first transistor (e.g., a main amplifier FET), a second transistor (e.g., a peaking amplifier FET), a combining node, and a shunt-inductance circuit. The first and second amplifiers and the combining node structure are integrally-formed with a semiconductor die, and the shunt-inductance circuit is integrated with the die. Outputs of the first and second transistors are electrically coupled to the combining node structure. The shunt-inductance circuit is electrically coupled between the combining node structure and a ground reference node. The shunt-inductance circuit includes a shunt inductance (e.g., including wirebond(s) and/or spiral inductor(s)) that is integrated with the semiconductor die. The multiple-path amplifier also may include an integrated phase shifter/impedance inverter coupled between the outputs of the first and second transistors, and which is configured to impart a 90-degree phase delay between intrinsic drains of the first and second transistors.