Envelope Tracking Voltage Correction for Wideband RF Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In mobile communication devices using 5G and 5G-NR technologies, RF signals in millimeter wave spectrums are susceptible to attenuation and interference, leading to misalignment of envelope tracking (ET) voltage with the RF signal's voltage envelope, causing distortion and reducing efficiency and linearity of power amplifiers across a wide modulation bandwidth.
Innovation Solution
A transmission circuit is configured with a transceiver circuit that applies complex filters to the RF signal or modulation vector to compensate for voltage distortion filters created by coupling power amplifier circuits with RF front-end circuits, thereby reducing unwanted distortion and improving efficiency and linearity across the modulation bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power amplifier circuit is coupled with RF front-end circuit to amplify RF signals, then signal transmission capability is improved, but voltage distortion filter is created causing misalignment between ET voltage and voltage envelope
Solution Approach 1:
The transceiver circuit applies a complex filter to the modulation vector or RF signal in advance to pre-compensate for the voltage distortion filter that will be created by the power amplifier circuit. This preliminary action ensures that the ET voltage remains aligned with the voltage envelope despite the subsequent distortion introduced by the power amplifier circuit coupling.
Solution Approach 2:
The system uses feedback by monitoring the interaction between the output reflection coefficient of the power amplifier circuit and the input reflection coefficient of the RF front-end circuit, and adjusting the complex filter parameters accordingly to maintain proper voltage alignment across the modulation bandwidth.
2Manufacturing precision
If complex filter is applied to compensate for voltage distortion filter, then voltage alignment is improved, but device complexity increases
Solution Approach 1:
The transceiver circuit is designed to perform multiple functions: it generates the RF signal from the modulation vector, applies the complex filter for distortion compensation, and manages the envelope tracking voltage. By integrating these functions into a single circuit block, the patent avoids adding separate dedicated circuits for each function, thereby limiting the increase in overall device complexity while achieving voltage alignment compensation.
3Power
If power amplifier amplifies RF signals based on modulated voltage, then signal power is increased, but instantaneous excessive compression and spectrum regrowth occur due to voltage distortion
Solution Approach 1:
The complex filter is applied to the modulation vector or RF signal before amplification to pre-compensate for the voltage distortion that would otherwise cause instantaneous excessive compression and spectrum regrowth. This preliminary compensation ensures that the power amplifier operates within its linear region and maintains signal quality while providing the necessary power amplification.
Data Source
AI summary
Envelope tracking (ET) voltage correction in a transmission circuit is provided. The transmission circuit includes a transceiver circuit and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from a time-variant modulation vector and the power amplifier circuit(s) amplifies the RF signal(s) based on a modulated voltage and provides the amplified RF signal(s) to a coupled RF front-end circuit. Herein, the transceiver circuit is configured to apply a complex filter(s) to the time-variant modulation vector and/or the RF signal(s) to compensate for a voltage distortion filter created across a modulation bandwidth of the RF signal(s) by coupling the power amplifier circuit with the RF front-end circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the voltage distortion filter to thereby improve efficiency and linearity of the power amplifier circuit(s) across the modulation bandwidth of the RF signal(s).