Adaptive Linearizer (ALIN) for Broadband Power Amplification

This Small Business Innovation Research Phase I project demonstrates an adaptive linearizer (ALIN) that uses a real-time digital signal processing technique to dramatically reduce harmonic and intermodulation distortion by approximately 24 dB over an extremely wide range of input frequencies, signal types, and amplitudes, and in rapidly changing environments (such as wide temperature variations). The technology adaptively tracks nonlinear distortion and subtracts out the errors. ALIN significantly improves the performance of RF amplifiers or the combination of devices in an RF transmit chain (e.g., amplifiers, mixers, digital-to-analog converters). This technology significantly improves the dynamic range, which enables very accurate and efficient synthesis of wideband signals at high intermediate frequencies (IF) or directly at high RF. By compensating for nonlinear compression effects in power amplifiers, the technology improves the amplifier efficiency by operating closer to saturation than with traditional amplifiers. Therefore, lower power, lower mass, lower cost amplifiers can be used in place of inefficient, high-power amplifiers. This pre-distortion waveform shaping significantly reduces out-of-band distortion components, which reduces interference and bandpass filter requirements. The linearizer is based on V Corp’s proprietary phase-shift polynomial model (which has been successfully tested using open-loop calibration methods). The enhancement of using adaptive calibration routines significantly simplifies or even eliminates system calibration. For example, an adaptive routine can be used to monitor the system output and interactively adjust the digital signal processing to minimize the nonlinear distortion without any external calibration signal sources or by interrupting the normal operation of the system. The real-time digital signal processing can be implemented in FPGA hardware, a DSP chip, a custom ASIC, or a software algorithm. The ALIN architecture will always exceed state-of-the-art because it can easily be upgraded as new, more powerful amplifier and converter products become available. V Corp is currently working with Analog Devices, Inc. on developing and packaging various high-performance converter technologies and digital signal processing techniques. During Phase I, V Corp will demonstrate the ALIN technique via testing with a power amplifier module and a digital-to-analog converter. During Phase II, a real-time implementation of the ALIN system will be implemented and integrated in a target system (e.g., advanced digital RF transceivers).