Dual-Drive Power Amplifier Topology for Low-Voltage Reliability
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Solution Overview
Problem
Traditional power amplifiers in CMOS technology face limitations in efficiency, output power, linearity, and reliability due to low breakdown voltages and intrinsic device losses, especially at higher frequencies, which are exacerbated by stringent requirements in 5G New Radio applications.
Innovation Solution
A dual-drive power amplifier configuration where transistors are driven out-of-phase at the gate and source terminals using a coupling network, allowing the source terminals to swing below ground potential, thereby increasing output power and efficiency while reducing the supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional common-source power amplifier topology is used, then the design is simple, but efficiency and output power are limited due to transistor knee voltage occupying a significant portion of supply voltage
Solution Approach 1:
The patent divides the single-drive approach into a dual-drive configuration, separately controlling the gate and source terminals of the transistor. This segmentation allows independent optimization of each terminal's drive signal, enabling the source to swing below ground potential and reducing the effective knee voltage impact, thereby improving efficiency without significantly complicating the overall amplifier architecture
Solution Approach 2:
The patent introduces a coupling network as an intermediary between the input signal and the transistor terminals. This coupling network distributes the drive signal to both gate and source terminals with appropriate phase relationships, enabling the source terminal to be driven out-of-phase and swing below ground, which effectively reduces the knee voltage penalty while maintaining design manageability
2Reliability
If supply voltage is reduced to ensure device reliability, then reliability improves, but output power and efficiency deteriorate
Solution Approach 1:
The patent inverts the conventional approach by driving the source terminal out-of-phase with the gate terminal, causing the source voltage to swing below ground potential. This inversion creates a larger effective voltage swing across the transistor without requiring a higher supply voltage, thereby maintaining or improving output power while using a reduced supply voltage that enhances device reliability
Solution Approach 2:
The patent changes the operating parameters by introducing out-of-phase driving at the source terminal, which fundamentally alters the voltage swing characteristics. This parameter change enables the amplifier to achieve higher output power and efficiency at reduced supply voltages, simultaneously improving reliability while maintaining power performance
3Device complexity
If transistors are driven only at the gate terminal, then the circuit is simple, but efficiency is limited because the transistor knee voltage becomes a significant portion of supply voltage
Solution Approach 1:
The patent segments the single gate-drive into dual terminal drives (gate and source), allowing separate optimization of each terminal's signal. This segmentation enables the source terminal to be driven in a manner that reduces knee voltage losses, improving efficiency while keeping the coupling network relatively simple
Solution Approach 2:
The coupling network serves as an intermediary that takes a single input signal and distributes it to both gate and source terminals with appropriate amplitude and phase relationships. This intermediary approach enables complex dual-drive functionality without requiring completely separate drive circuits, thus limiting the increase in overall circuit complexity while achieving reduced device losses
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 dual-drive power amplifier configuration significantly enhances output power, linearity, and efficiency, maintaining high reliability even at reduced supply voltages, and supports broadband operations with lower device AM-PM and AM-AM distortion.
Implementation Method 1
a first transmission line section of a pair is configured to transmit an input signal Vin through to drive a gate of the opposite transistor
Implementation Method 2
the second transmission line section is grounded at one end and coupled with the first transmission line section such that a coupled portion αVin of the input signal Vin drives the source terminal
Data Source
AI summary
A dual-drive power amplifier (PA) where the PA core includes a differential pair of transistors M1 and M2 that are driven by a coupling network having two transmission-line couplers, where a first transmission line section of a coupler is configured to transmit an input signal Vin through to drive a gate of the opposite transistor, while the second transmission line section is grounded at one end and coupled with the first transmission line section such that a coupled portion αVin of the input signal Vin drives the source terminal of a corresponding transistor. The arrangement of the coupling network allows the source terminals to be driven below ground potential. Embodiments disclosed here further provide an input matching network, a driver, an inter-stage matching network, and an output network for practical implementation of the PA core.