Transceiver Phase Correction for Wideband AM-PM Distortion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing transceiver circuits suffer from amplitude-to-phase (AM-PM) distortion due to group delay interactions between power amplifier and RF frontend circuits, leading to undesired amplitude distortion and spectrum regrowth, particularly in wide modulation bandwidths.
Innovation Solution
A transceiver circuit is configured to determine a phase correction term from a time-variant input vector and apply it to correct AM-PM errors, using a delay equalizer and phase correction circuit to convert variable group delays into constant delays, achieving linear phase errors across transmission frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power amplifier circuit amplifies RF signal based on modulated voltage, then signal power is increased for transmission, but amplitude-to-phase distortion is generated due to group delay interaction with RF frontend circuit
Solution Approach 1:
The patent applies preliminary action by calculating and storing phase correction terms in advance for different power levels before transmission occurs. The lookup table pre-computes the phase distortion compensation values based on the known characteristics of the power amplifier and RF frontend circuit interaction, so that when transmission occurs, the correction can be applied immediately without real-time computation delays.
Solution Approach 2:
The patent implements feedback by using the measured or characterized phase distortion from the power amplifier-RF frontend interaction to generate correction terms. The system effectively creates a feedback loop where the distortion characteristics are measured, processed into correction values, and then applied to compensate for the distortion in subsequent transmissions.
2Reliability
If phase correction is applied across wide modulation bandwidth, then amplitude distortion and spectrum regrowth are prevented, but computational complexity increases
Solution Approach 1:
The patent significantly reduces computational complexity during transmission by pre-calculating phase correction terms for different power levels and storing them in a lookup table. During actual transmission, the system simply performs a table lookup based on the current power level and applies the pre-computed correction, avoiding real-time complex calculations across the wide modulation bandwidth.
Solution Approach 2:
The patent uses a lookup table that stores pre-computed phase correction terms for different power levels. This copying approach allows the system to reuse the same correction values for signals with similar power characteristics, avoiding the need to perform unique complex calculations for each transmitted signal while maintaining correction accuracy across the modulation bandwidth.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Amplitude-to-phase (AM-PM) error correction in a transceiver circuit is provided. The transceiver circuit is configured to generate a radio frequency (RF) signal from a time-variant input vector for transmission in one or more transmission frequencies. In embodiments disclosed herein, the transceiver circuit is configured to determine a phase correction term from the time-variant input vector and apply the determined phase correction term to the time-variant input vector to thereby correct an AM-PM error(s) in the RF signal. By correcting the AM-PM error(s) in the transceiver circuit, it is possible to prevent undesired amplitude distortion and/or spectrum regrowth in any of the transmission frequencies, particularly when the RF signal is modulated across a wide modulation bandwidth (e.g., ≥ 200 MHz).