Transceiver AM-AM Error Correction via Frequency Equalization
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Solution Overview
Problem
Wireless communication circuits face amplitude-amplitude (AM-AM) errors due to interaction between power amplifier and RF frontend circuits, leading to amplitude distortion across wide modulation bandwidths, which conventional methods address with complex memory digital predistortion (mDPD) coefficients, increasing implementation and calibration complexity.
Innovation Solution
A transceiver circuit with a frequency equalization circuit and gain error correction circuit applies filters to linearize gain errors, eliminating modulation frequency dependency by superimposing linearized gain errors onto a reference frequency, reducing complexity and correcting AM-AM errors across the modulation bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory digital predistortion (mDPD) coefficients are used to correct AM-AM error, then amplitude distortion is corrected, but device complexity and calibration difficulty increase
Solution Approach 1:
The patent extracts and eliminates the modulation frequency dependency from the AM-AM error correction process. By identifying that the error characteristic is independent of modulation frequency, the solution removes this complexity variable and uses a single reference frequency for all corrections across the entire modulation bandwidth, thereby reducing the complexity of required correction coefficients.
Solution Approach 2:
The patent creates a universal correction approach where a single reference frequency correction is applied across all modulation frequencies. The frequency equalization circuit and gain error correction circuit work together to provide a multi-functional correction system that handles the entire modulation bandwidth using one reference point, eliminating the need for separate corrections at each frequency.
2Reliability
If frequency equalization and gain error correction are applied, then AM-AM error is corrected across modulation bandwidth, but processing time increases
Solution Approach 1:
The patent applies frequency equalization and gain error correction in advance of the power amplification process. By pre-equalizing the input signal and pre-correcting gain errors before the signal enters the power amplifier, the system eliminates the need for complex post-processing corrections, thereby reducing overall processing time despite the additional correction steps.
3Power
If power amplifier amplifies RF signal, then signal power is increased, but AM-AM error is introduced
Solution Approach 1:
The patent applies preliminary anti-action by introducing frequency equalization and gain error correction before the power amplification process. These pre-corrections counteract the AM-AM error that will be introduced by the power amplifier, effectively neutralizing the harmful effect before it occurs and maintaining amplitude accuracy across the modulation bandwidth.
Data Source
AI summary
Low-complexity amplitude and phase (AM-PM) error correction in a transceiver circuit is provided. In embodiments disclosed herein, a transceiver circuit is configured to equalize an input vector to thereby correct an AM-AM error across a modulation bandwidth of the wireless communication circuit. Unlike conventional methods where complicated memory digital predistortion (mDPD) coefficients must be defined and calibrated for each modulation frequency within the modulation bandwidth, the transceiver circuit is configured herein to eliminate modulation frequency dependency of the AM-AM error. As a result, it is possible to correct the AM-AM error across the modulation bandwidth with reduced complexity to thereby improve efficiency and linearity of the wireless communication circuit.