Transceiver Delay Equalization for Wideband AM-PM Error Correction
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Solution Overview
Problem
In mobile communication devices, the interaction between power amplifier circuits and RF frontend circuits can cause group delays in RF signals, leading to amplitude-to-phase (AM-PM) distortions, especially when the RF signal is modulated across a wide bandwidth.
Innovation Solution
A transceiver circuit is configured with a delay equalizer circuit and a phase correction circuit to determine and apply a phase correction term to the RF signal, converting variable group delays into constant group delays and correcting phase errors to prevent AM-PM distortions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power amplifier circuit amplifies RF signal based on modulated voltage, then RF signal power is boosted to higher power, but group delay interaction causes AM-PM distortion in the RF signal
Solution Approach 1:
The patent applies preliminary action by measuring the group delay of the power amplifier circuit in advance across multiple frequencies and frequencies, then using this pre-acquired data to calculate compensation coefficients that are stored for later use during signal transmission, avoiding real-time calculation delays
Solution Approach 2:
The patent implements feedback by measuring the actual group delay of the power amplifier circuit, using this measurement to calculate compensation coefficients, and applying these coefficients to compensate for AM-PM distortion in the transmitted RF signal, creating a closed-loop correction system
2Productivity
If RF signal is modulated across wide modulation bandwidth (≥200 MHz), then data rate is increased, but AM-PM distortion causes undesired amplitude distortion and spectrum regrowth
Solution Approach 1:
The patent applies parameter changes by measuring group delay across multiple frequencies and power levels, calculating compensation coefficients based on these measurements, and dynamically adjusting the phase of the RF signal using these coefficients to compensate for AM-PM distortion across wide bandwidths
Solution Approach 2:
The patent replaces mechanical/analog amplitude control with digital signal processing by measuring group delay characteristics, calculating digital compensation coefficients, and applying phase correction through digital signal manipulation to achieve amplitude distortion compensation
3Stability of the object's composition
If delay equalizer circuit equalizes time-variant input vector based on complex filter, then variable group delay is converted into constant group delay, but circuit complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-measuring the group delay characteristics of the power amplifier circuit across multiple frequencies and power levels, storing these measurements, and using them to pre-calculate compensation coefficients that are later applied during signal transmission, avoiding real-time complex calculations
Solution Approach 2:
The patent creates a digital model (copy) of the power amplifier circuit's group delay characteristics by measuring and storing data across multiple frequencies and power levels, then using this copied model to calculate compensation coefficients without needing to physically analyze the circuit in real-time
Data Source
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).