Ring Load Modulation Network for Low-Loss mm-Wave Power Amplifiers
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Solution Overview
Problem
Existing high-efficiency power amplifiers for 5G wireless networks face challenges in achieving efficient load modulation, particularly at millimeter-wave frequencies, due to the need for precise phase and amplitude control and the limitations of dynamic load modulation networks which require large banks of switches and are difficult to scale.
Innovation Solution
A passive, tunable on-chip load modulation network using a ring transmission line with switched inputs to provide unique impedance transformations, allowing for efficient impedance tuning between 15 and 80 ohms with minimal imaginary load variation, enabling efficient power handling and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If dynamic load modulation uses switches to change output tuning elements, then efficiency for desired output power is optimized, but large banks of switches are required which cannot access large areas of the Smith chart without significant loss
Solution Approach 1:
The load modulation network is segmented into multiple discrete impedance transformation stages, each providing a specific impedance ratio. By cascading these segmented stages with different transformation ratios, the system can access different regions of the Smith chart without requiring a single complex switch bank, thereby reducing insertion loss while maintaining efficiency optimization capability.
Solution Approach 2:
The invention changes the parameter of impedance transformation by using multiple stages with different transformation ratios rather than a single stage. This allows the system to achieve the desired load modulation effect with lower loss by selecting appropriate transformation ratios for each stage based on the operating conditions.
2Speed
If DLM is scaled to mm-wave bands, then high-frequency operation is achieved, but large parasitic capacitance and resistance associated with switch or varactor components increase
Solution Approach 1:
The invention extracts the switching function from the load modulation network and places it at the input stage, separate from the mm-wave signal path. This removes the parasitic capacitance and resistance of switches and varactors from the high-frequency signal path, enabling clean operation at mm-wave frequencies without the harmful parasitic effects.
Solution Approach 2:
The input-stage switch acts as an intermediary that controls the activation of different impedance transformation stages without being part of the mm-wave signal path. This mediator approach allows the switch's parasitic effects to be isolated from the high-frequency operation, enabling successful scaling to mm-wave bands.
3Use of energy by moving object
If multiple amplifiers are used for load modulation, then backoff efficiency is improved, but device complexity and difficulty of implementation increase
Solution Approach 1:
The invention makes a single power amplifier universal by enabling it to operate efficiently across multiple power levels through dynamic load modulation. The amplifier can adapt its load impedance to maintain high efficiency whether operating at peak power or backoff power levels, eliminating the need for multiple dedicated amplifiers while achieving the same efficiency benefits.
Solution Approach 2:
The invention introduces dynamic load modulation to a single amplifier, allowing its load impedance to change dynamically based on the desired output power level. This dynamic adaptation enables the amplifier to maintain high efficiency across different operating conditions without requiring multiple static amplifier configurations.
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 achieves improved efficiency and power handling, with measured efficiency improvements of up to 37% compared to ideal class B back-off efficiency, and supports high-power handling with low insertion losses, suitable for millimeter-wave frequencies.
Implementation Method 1
A first switched input is connected to a second point on the ring transmission line, the second point being located on the ring transmission line to provide a first impedance transformation. A second switched input is connected to a third point on the ring transmission line, the third point being located to provide a second impedance transformation that is unique from the first impedance transformation.
Data Source
AI summary
A passive, tunable on-chip load modulation network for a high-efficiency power amplifier includes a ring transmission line. An output is connected to a first point on the ring transmission line. A first switched input is connected to a second point on the ring transmission line, the second point being located on the ring transmission line to provide a first impedance transformation. A second switched input is connected to a third point on the ring transmission line, the third point being located to provide a second impedance transformation that is unique from the first impedance transformation.