Complementary Cascode Power Amplifier for 5G Linearity
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Solution Overview
Problem
Power amplifiers in 5G systems face challenges in achieving higher linearity for high-order modulation and reliability issues such as hot carrier injection, time-dependent dielectric breakdown, and bias temperature instability, which affect their performance and lifespan.
Innovation Solution
The proposed power amplifier structure incorporates complementary transistors connected in series with inductors to reduce parasitic capacitance, enhance power output, and improve reliability, featuring a cascode amplifier configuration with p-type and n-type transistors and transformers to split and combine signals effectively, thereby mitigating AM-PM distortion and increasing linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power amplifier structures are used, then device complexity is reduced, but linearity and reliability deteriorate due to parasitic capacitance and HCl/TDDB/BTI issues
Solution Approach 1:
The power amplifier is divided into multiple stages including a first stage with a first transistor and a second stage with a second transistor. Each stage can be independently optimized for specific functions such as gain, linearity, and power output. This segmentation allows the circuit to achieve high reliability and linearity while managing complexity through modular design.
Solution Approach 2:
Inductors are introduced as intermediary elements between the transistors and power supplies, and between different circuit nodes. These inductors serve as mediators that cancel parasitic capacitance effects, improve power transfer, and enhance overall circuit performance without requiring complete redesign of the transistor structures themselves.
2Power
If inductors are added to cancel parasitic capacitance and enhance power output, then power and linearity improve, but device complexity and power loss increase
Solution Approach 1:
The inductors are designed with specific inductance values optimized for the operating frequency range. By carefully selecting and tuning the inductance parameters, the circuit achieves maximum power output while minimizing energy loss. The inductance values are chosen to resonate with and cancel the parasitic capacitance at the desired operating frequencies.
Solution Approach 2:
The inductors are configured to operate at specific resonant frequencies, creating periodic energy storage and release cycles that enhance power output during the active phases while minimizing losses during transition phases. This periodic operation allows the circuit to efficiently transfer energy at the designed operating frequencies.
3Reliability
If complementary transistors are used in series configuration, then linearity and reliability improve, but device complexity increases
Solution Approach 1:
Complementary transistors (n-type and p-type) are merged in a series configuration where they work together to achieve improved linearity and reliability. The combining of opposite-polarity transistors allows the circuit to handle both positive and negative signal cycles efficiently while canceling out certain non-linear effects that would be present in single-transistor designs.
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
This configuration enhances the reliability and linearity of power amplifiers, reduces power loss, and increases the overall performance by providing maximum power with efficient inductance settings, addressing the reliability and linearity concerns in 5G systems.
Implementation Method 1
The inductor is configured to reduce parasitic capacitance at the connecting node
Implementation Method 2
providing maximum power with efficient inductance settings
Data Source
AI summary
A power amplifier structure includes at least one power amplifier circuit. The power amplifier circuit includes a transistor of a first type connected in series with a transistor of a second type connected between the same voltage supply. In a non-limiting nonexclusive example, an n-type transistor is connected in series with a p-type transistor connected between Vdd. The power amplifier structure can include two amplifier circuits configured in a differential amplifier structure. The differential amplifier structure includes two amplifier circuits operably connected in parallel between the same voltage supply.