Dual-Supply Doherty Power Amplifier with Progressive Envelope Tracking
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Solution Overview
Problem
Doherty-type power amplifiers in radio frequency transmitters face challenges in achieving high energy efficiency and linearity during power amplification, particularly in meeting the power level control requirements of advanced wireless communication technologies like 5G-NR.
Innovation Solution
The implementation of an envelope tracking circuitry with dual instantaneous voltage enhanced rapid tracking (DiVeRT) that generates two modulated power supply voltages from a single tracker circuit, separately modulating the driver and final output stages of power amplifiers, and employing a Doherty and dual envelope tracking method (D2E) to enhance bias control and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Doherty amplifier is used to provide power amplification options, then power level control requirements can be met, but energy efficiency and linearity during power amplification need improvement
Solution Approach 1:
The power amplifier is segmented into a carrier amplifier and a peaking amplifier that operate at different power levels. The carrier amplifier handles average power while the peaking amplifier provides peak power supplementation, allowing each segment to operate in its optimal efficiency range and reducing overall energy loss.
Solution Approach 2:
The amplifier system dynamically switches between carrier-only operation and combined carrier-peaking operation based on the instantaneous power demand. The peaking amplifier is progressively turned on as power demand increases, enabling the system to adapt its configuration to maintain high efficiency across varying power levels.
2Power
If a Doherty amplifier is used to provide power amplification options, then power level control requirements can be met, but linearity during power amplification needs improvement
Solution Approach 1:
Envelope tracking circuitry provides feedback control by monitoring the instantaneous power demand and adjusting the supply voltages to both the carrier and peaking amplifiers accordingly. This feedback mechanism ensures that the amplifiers operate in a linear region during power amplification, maintaining signal fidelity while meeting power level control requirements.
Solution Approach 2:
The supply voltages to the amplifiers are dynamically changed based on the envelope of the modulating signal. By varying the supply voltage parameters in sync with the signal envelope, the amplifiers maintain optimal operating points that preserve linearity across different power levels.
3Power
If average power tracking amplifiers are used, then power amplification is provided, but power-added efficiency is lower compared to envelope tracking
Solution Approach 1:
The envelope tracking system dynamically adjusts the supply voltages to match the instantaneous power demand of the amplifier. Unlike average power tracking that maintains a fixed supply voltage, this dynamic adjustment ensures the amplifier receives optimal power supply at each moment, significantly reducing energy loss and improving power-added efficiency by up to 18%.
Data Source
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AI summary
A power amplifier system (10) having a carrier amplifier (16) having a first supply node, a peaking amplifier (20) having a second supply node, and envelope tracking (ET) circuitry is disclosed. The ET circuitry has a first tracking amplifier (42) that generates a first voltage signal at the first supply node, a second tracking amplifier (50) that generates a second voltage signal at the second supply node, and a transistor (62) coupled between the first supply node and the second supply node . A control circuit (70) has a first input coupled to an output of both or either of the first tracking amplifier (42) and the second tracking amplifier (50) and a control output terminal coupled to a control input terminal of the transistor (61), wherein the control circuit (70) is configured to progressively turn on the transistor (62) to pass current from the first supply node to the second supply node as the peaking amplifier (20) progressively becomes active.