Auto-Transformer Power Combiner for Efficient CMOS RF Amplifiers
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Solution Overview
Problem
CMOS power amplifiers for mobile wireless communication face challenges due to low breakdown voltage and high peak-to-average power ratio (PAPR) of OFDM-based modulation schemes, leading to reduced power efficiency and heat dissipation issues in battery-powered devices.
Innovation Solution
A distributed power amplifier circuit utilizing a chain of auto transformers to combine output signals from multiple sub-amplifiers, with configurable sub-amplifiers and separate power supply nodes for improved efficiency, and configuration switches to optimize power usage based on required output power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMOS technology is used for power amplifiers in mobile devices, then cost is reduced, but power efficiency deteriorates due to low breakdown voltage
Solution Approach 1:
The power amplifier is divided into multiple sub-amplifier stages (first sub-amplifier, second sub-amplifier, etc.), each operating at lower power levels. This segmentation allows CMOS transistors to operate within their safe voltage limits while collectively delivering the required total output power, thus maintaining both cost-effectiveness and power efficiency.
Solution Approach 2:
Multiple sub-amplifier outputs are combined through a power combiner network to achieve the desired total output power. This merging approach enables each individual CMOS-based sub-amplifier to operate efficiently at lower power levels while the combined output meets the high power requirements, resolving the contradiction between CMOS cost advantages and power efficiency needs.
2Use of energy by moving object
If Doherty-type PAs are used to improve power efficiency, then power efficiency is improved, but device complexity increases and space requirements increase
Solution Approach 1:
The power amplifier is segmented into multiple independent sub-amplifier stages that can be individually controlled and optimized. Each sub-amplifier operates as a separate unit with its own power supply voltage, allowing for simplified individual designs that collectively achieve high power efficiency without requiring the complex impedance matching networks and transmission lines characteristic of Doherty architectures.
Solution Approach 2:
The power amplifier employs dynamic power supply voltage control where each sub-amplifier's supply voltage can be independently adjusted based on operating conditions. This dynamic adaptation allows the circuit to optimize power efficiency across different output power levels without the fixed structural complexity of traditional Doherty designs, making it more suitable for mobile devices with limited space.
3Power
If multiple sub-amplifiers are used to increase output power, then output power is increased, but insertion losses increase reducing power efficiency
Solution Approach 1:
The invention changes the operating parameters of each sub-amplifier by providing different power supply voltages to different stages. This parameter optimization allows each sub-amplifier to operate at its most efficient point, minimizing insertion losses while collectively delivering high output power. The power combiner network is also designed with optimized impedance matching to minimize loss during signal combination.
Solution Approach 2:
The power amplifier uses multiple identical or similar sub-amplifier stages that replicate the same efficient circuit topology. Each sub-amplifier is designed to have minimal insertion loss, and by copying this optimized design across multiple stages and combining their outputs, the system achieves high total power while maintaining low per-stage losses, thereby improving overall power efficiency.
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
Enhances power efficiency by reducing insertion losses and allowing for adaptive power supply management, thereby extending battery life and reducing heat dissipation in mobile devices.
Implementation Method 1
The auto transformers are operatively connected in series via said interconnection terminals, thereby forming a chain of auto transformers
Data Source
AI summary
A distributed power amplifier circuit is disclosed. The distributed power amplifier circuit comprises an amplifier arrangement comprising a plurality of sub amplifiers, each having an output port for outputting an output signal of the sub-amplifier and an output combiner network for combining the output signals from the sub amplifiers. The output combiner network includes, for each sub amplifier, an associated auto transformer operatively connected to the output port of the sub amplifier for receiving the output signal of the sub amplifier. The auto transformers each have a first interconnection terminal and a second interconnection terminal. The auto transformers are operatively connected in series via the interconnection terminals, thereby forming a chain of auto transformers having a first end and a second end, wherein the first end is arranged to be connected to an antenna.