Radar Pulse Pre-Distortion for GaN Amplifier Phase Stability
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Solution Overview
Problem
Modern radar systems face interpulse instability due to thermal and electrical transients in GaN power amplifiers, which affect phase stability and clutter rejection, leading to inefficiencies and reduced target detection capabilities.
Innovation Solution
A digital pre-distortion technique is applied to radar signals before power amplification, using a behavioral model to correct for amplitude and phase transients by generating pre-distortion coefficients based on sequence differences between pulse sequences, thereby mitigating the effects of interpulse instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If GaN power amplifiers are used to achieve high power density and efficiency, then power output and energy efficiency are improved, but thermal and electrical transients cause interpulse instability and phase drift
Solution Approach 1:
The patent applies digital pre-distortion to the radar signal before power amplification. A behavioral model characterizes the amplifier's transient response, and pre-distortion coefficients are calculated and applied to the synthesized signal prior to amplification. This preliminary correction compensates for anticipated thermal and electrical transients, allowing the system to achieve desired phase stability without sacrificing the high power density benefits of GaN amplifiers.
2Adaptability or versatility
If multiple diverse radar waveforms are transmitted in close succession for multifunction operation, then radar versatility and mission capability are improved, but amplifier thermal transients increase causing amplitude and phase distortion
Solution Approach 1:
The system performs rapid waveform switching for multifunction operation while applying pre-distortion coefficients calculated from a behavioral model that accounts for transient effects. By predicting and compensating for thermal transients before they distort the signal, the patent enables diverse waveform transmission without sacrificing signal fidelity or clutter rejection performance.
3Stability of the object's composition
If conventional fill pulses are added to mitigate interpulse instability, then phase stability is improved, but system productivity and target detection efficiency deteriorate due to wasted time
Solution Approach 1:
Instead of adding fill pulses after waveform switching to wait for thermal stabilization, the patent applies pre-distortion coefficients before transmission that proactively compensate for anticipated transients. This allows immediate transmission of diverse waveforms without stability degradation, eliminating the need for fill pulses and maximizing productivity and target detection efficiency.
4Stability of the object's composition
If digital pre-distortion is applied to correct transient effects, then phase stability and clutter rejection are improved, but computational complexity and processing requirements increase
Solution Approach 1:
The patent creates a behavioral model that copies or replicates the amplifier's transient response characteristics through cross-correlation analysis of reference and amplified signals. This model is then used to generate pre-distortion coefficients that compensate for the identified transients. By copying the transient behavior rather than directly controlling the physical amplifier during operation, the system achieves phase stability with manageable computational complexity.
Data Source
AI summary
A method is provided for correcting radar signal transient variation induced by power amplification in a pulse radar transmitter. The method includes establishing a first plurality of characteristics of a first pulse sequence having a digital pulse; establishing a second plurality of characteristics of a second pulse sequence having a plurality of digital pulses; comparing the first and second pluralities of characteristics to determine a sequence difference; providing pre-distortion coefficients for the plurality of digital pulses corresponding to the signal transient variation in response to the sequence difference; and applying the coefficients to the plurality of digital pulses prior to the power amplification.