Double Harmonic Gate Termination for Wideband Doherty PAs
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Solution Overview
Problem
Doherty power amplifiers face challenges in maintaining high power efficiency and reducing intermodulation distortion, particularly in wideband applications with bandwidths greater than or equal to 400 MHz, due to the limitations of traditional single harmonic gate terminations.
Innovation Solution
Implementing a double harmonic gate termination circuit with two parallel LC network circuits and a common mode ground inductor to short a range of second harmonics, covering a wider bandwidth and reducing intermodulation distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional single harmonic gate termination is used, then the circuit complexity is low, but the bandwidth coverage is insufficient for wideband applications (>=400 MHz)
Solution Approach 1:
The single harmonic gate termination circuit is segmented into two separate LC network circuits, each tuned to different frequency ranges. This segmentation allows the circuit to cover a broader bandwidth (>=400 MHz) while maintaining manageable complexity through modular design.
Solution Approach 2:
The double harmonic gate termination circuit serves multiple functions: it provides harmonic termination across a wide bandwidth, reduces intermodulation distortion, and maintains power efficiency. The two LC networks work together to achieve universal coverage across the entire operating bandwidth.
2Adaptability or versatility
If a double harmonic gate termination circuit is implemented to cover wider bandwidth, then the bandwidth coverage is improved, but the device complexity increases
Solution Approach 1:
Two LC network circuits are merged into a single integrated double harmonic gate termination circuit. The circuits are combined in parallel configuration, sharing common connections to the gate terminal, which reduces overall complexity compared to implementing separate termination circuits.
Solution Approach 2:
Each LC network circuit is optimized for specific frequency ranges within the total bandwidth. The first LC network handles lower frequency harmonics while the second handles higher frequencies, allowing each component to be locally optimized for its specific function.
3Use of energy by moving object
If harmonic termination is extended to cover broader frequency ranges, then the power added efficiency is improved, but the intermodulation distortion reduction becomes more challenging
Solution Approach 1:
The circuit converts harmful second harmonic signals into beneficial effects by terminating them at the gate. The doubled harmonic termination absorbs and dissipates harmonic energy that would otherwise cause intermodulation distortion, transforming a harmful factor into a power efficiency improvement.
Solution Approach 2:
The LC network circuits act as intermediary elements between the amplifier output and the gate terminal. They mediate the interaction between fundamental signals and harmonic frequencies, providing a controlled path for harmonic termination while isolating the active device from harmful intermodulation effects.
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 double harmonic gate termination circuit enhances power added efficiency (PAE) and improves amplifier performance by effectively handling broader frequency ranges while maintaining low size and complexity, making it suitable for wireless devices with high peak-to-average power ratio modulation signals.
Implementation Method 1
a first LC network circuit of the two LC network circuits is configured to resonate between a second harmonic frequency of a low end frequency of the input frequency range and a second harmonic frequency of a center band frequency of the input frequency range. In some implementations, a second LC network circuit of the two LC network circuits is configured to resonate between the second harmonic frequency of the center band frequency and a second harmonic frequency of a high end frequency of the input frequency range.
Data Source
AI summary
Double harmonic gate terminations are used to increase power efficiency in Doherty power amplifiers. These technologies increase power efficiency in Doherty power amplifiers through wave shaping using double harmonic gate terminations. The double harmonic gate terminations span a targeted input frequency range over which the power amplifiers operate. The double harmonic gate terminations cover a wider bandwidth than a single harmonic gate termination. The harmonic termination can include more than two terminations to cover a broader range of frequencies or to cover a wider bandwidth. It may be desirable to implement the broad harmonic gate termination using two gate terminations to keep the size of the circuit and module small and to reduce costs relative to other solutions for harmonic gate terminations that utilize a greater number of components or components of a larger size.