Cascode Doherty Amplifier Bias Switching for High-Frequency ET Efficiency
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Solution Overview
Problem
The efficiency of amplifier circuits degrades as the frequency of high frequency signals increases when using digital envelope tracking (ET) technology.
Innovation Solution
An amplifier circuit design that includes cascode-connected carrier and peak amplifiers, a combiner circuit, a bias circuit, and switches controlled by digital control signals, which dynamically adjust power supply voltages based on envelope signals to optimize efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If digital envelope tracking technology is used to improve power-added efficiency, then efficiency is improved at lower frequencies, but efficiency degrades as the frequency of the high frequency signal increases
Solution Approach 1:
The amplifier is divided into multiple amplifier elements connected in cascode configuration, allowing each element to operate at optimized bias points for different frequency ranges, thereby maintaining efficiency across varying frequencies
Solution Approach 2:
The bias circuit dynamically adjusts the bias current supplied to the amplifier elements based on the operating frequency and signal conditions, enabling the amplifier to adapt its efficiency characteristics to match the input signal frequency
Data Source
AI summary
An amplifier circuit is an amplifier circuit that receives a plurality of discrete power supply voltages and includes a carrier amplifier, a peak amplifier, a combiner circuit that combines a high frequency signal outputted from the carrier amplifier and a high frequency signal outputted from the peak amplifier together, a bias circuit that supplies a first bias current to the peak amplifier, a digital control terminal that receives a digital control signal based on an envelope signal, and a switch that is connected to the digital control terminal and switches between connection and disconnection between the bias circuit and the peak amplifier. Each of the carrier amplifier and the peak amplifier includes a plurality of amplifier elements that are cascode-connected.