Symmetric Doherty Combiner Layout for Low-Loss 60 GHz Amplifiers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Doherty power amplifiers for millimeter-wave communication, particularly at the 60-GHz band, face challenges in achieving high efficiency due to significant losses in on-chip combiner networks and layout complexity, limiting size reduction and integration into larger arrays.
Innovation Solution
A compact Doherty power amplifier design featuring a symmetric combiner with only two lumped elements and an impedance converter, reducing combiner loss and simplifying the layout, while maintaining high power-added efficiency (PAE) across a wide range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional Doherty power amplifier uses quarter-wave transmission lines for load modulation, then the amplifier can achieve peak power output, but the transmission line introduces significant loss that degrades back-off efficiency
Solution Approach 1:
The patent extracts and removes the quarter-wave transmission line from the Doherty amplifier structure, replacing it with an impedance converter. This eliminates the significant loss introduced by the transmission line while maintaining the load modulation function, thereby improving back-off efficiency without sacrificing peak power output capability
Solution Approach 2:
The patent changes the impedance transformation approach by using an impedance converter with specific impedance values (e.g., 2:1 or 4:1 ratio) instead of quarter-wave transmission lines. This parameter change in the impedance transformation mechanism reduces loss and improves back-off efficiency while maintaining peak power performance
2Loss of energy
If a symmetric Doherty power amplifier design uses five lumped-elements in the combiner, then the combiner loss can be reduced, but the layout complexity increases and efficiency decreases due to combined losses
Solution Approach 1:
The patent extracts and removes three of the five lumped-elements from the combiner structure, simplifying it to only two essential lumped-elements. This reduction eliminates unnecessary complexity in the layout while maintaining the low combiner loss characteristic, thereby resolving the contradiction between loss reduction and complexity increase
Solution Approach 2:
The patent uses a simplified combiner design that copies only the essential functional elements from the five-element design, retaining the two critical lumped-elements needed for impedance transformation while eliminating redundant components. This reduces layout complexity and combined losses
3Power
If an antenna-based Doherty structure is used, then power-added efficiency at back-off can be improved, but integration into larger arrays becomes difficult and thermal sinking is restricted
Solution Approach 1:
The patent replaces the antenna-based mechanical structure with an integrated circuit implementation using an impedance converter and lumped-elements. This substitution maintains the high power-added efficiency at back-off while enabling easy integration into larger arrays and improving thermal sinking capabilities through standard PCB or chip-based heat dissipation paths
Data Source
AI summary
An input signal is input to a main power amplifier and an auxiliary power amplifier. A combiner is connected to an output of the main power amplifier and an output of the auxiliary power amplifier. The combiner includes an impedance converter, first and second lumped elements. The impedance converter is connected to a combining point. The first lumped element is connected between the output of the main power amplifier and the combining point. The second lumped element is connected between the output of the auxiliary power amplifier and the combining point. A line length between the output of the main power amplifier and the combining point is the same as that between a line length between the output of the auxiliary power amplifier and the combining point.