MaXentric Designs and Optimizes Envelope Tracking Power Amplifiers for 5G LTE Using NI AWR Software
MaXentric Technologies, LLC is a specialty R&D firm that provides product design, development, and manufacturing services for the military defense market, as well as telecommunications/broadcast commercial markets. MaXentric products include simple low-cost millimeterwave broadband wireless transceivers, passive radio-frequency identification (RFID) readers, and high-efficiency envelope-tracking (ET) power amplifiers (PAs). Typical applications include intelligence, surveillance, and reconnaissance (ISR) components, high-bandwidth wireless communications, electronic warfare (EW), broadband high-efficiency PAs, and more.
The Design Challenge
PAs are an integral part of all cellular phones, base stations, and radio systems and represent one of the most expensive component sub-assemblies in modern wireless infrastructure equipment. Both performance and cost are important drivers in system design and efficiency, making physical size, linearity, and reliability among the principal challenges. As systems and their waveforms get more complicated, new and innovative techniques and materials must be used to provide the required performance.
The increasing demand for higher data rates and larger signal bandwidth, while maintaining signal integrity, have led to the use of signals with non-constant envelope and high peak-to-average power ratio (PAPR). In conventional fixed-bias PAs, the maximum efficiency occurs at saturation, with a single-tone signal. As the PA operates at power levels away from saturation, the efficiency degrades. This creates an issue in the presence of high PAPR signals (such as orthogonal frequency-division multiplexing [OFDM]), where the average power is well below saturation.
The challenge for the MaXentric design team was to develop an ETPA using real-time efficiency and linearity measurements for optimizing ETPA design, with flexibility to accommodate different 5G signals. As talk of future 5G LTE systems calls for signal bandwidths of greater than 100 MHz, the need for an evaluation platform with 500 MHz was crucial.
MaXentric designers chose NI AWR Design Environment, specifically Microwave Office circuit design software, to design and optimize their ETPA, as well as the NI vector signal transceiver (VST) for RF signal generation and the NI arbitrary waveform generator (AWG) for envelope signal generation. On-board tuning and final optimization of the PA impedance matching network was performed with Microwave Office software, which provided nonlinear harmonic balance circuit simulation in conjunction with design features such as load-pull analysis, transient analysis, circuit envelope, and verification through circuit/electromagnetic (EM) co-simulation via NI AWR Design Environment’s AXIEM 3D planar EM simulator.
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