RF Power Amplifier Module Research Articles

N77 Radio Frequency Power Amplifier Module for 5G New-Radio High-Power User Equipment Mobile Handset Applications

This paper presents a highly efficient 5G New-Radio (NR) RF power amplifier module (PAM). The n77 PAM consists of a high-voltage differential-topology 2 μm GaAs HBT power amplifier, a CMOS controller, a silicon-on-insulator (SOI) switch, an integrated passive device (IPD) bandpass filter, a low-noise amplifier (LNA), and a bi-directional coupler. This PAM generates a saturation output power of 32.7 dBm including the loss of the SOI switch and output filter. The designed n77 PAM is tested with a commercial envelope tracker IC (ET-IC). The designed PAM with an ET-IC achieves an ACLR of −37 dBc at a 27 dBm output power with a DFT-s-OFDM QPSK 100 MHz NR signal and saves a dc power consumption of 950 mW compared to the APT mode. For the CP-OFDM 256QAM with the most stringent EVM requirements, it achieves an EVM of 1.22% at 23 dBm and saves 640 mW compared to the APT mode.

Implications of thermal instability on HBT power amplifier reliability

Thermal stability is one of several important performance requirements for RF power amplifier modules used for cellular applications. In this work, the conditions for thermal instability in an HBT array for shared and individual ballast configurations are evaluated using experimental results from RF biased life test (RFHTOL) and ADS simulations. The instability is modest under nominal operating conditions, but becomes more severe at elevated temperatures which are frequently used in accelerated reliability tests such as RFHTOL. Thermally unstable power cells exhibit current crowding where one or two cells hog most of the current, resulting in localized hot spots from increased power dissipation density. This paper discusses the link between reliability failures during RFHTOL reliability testing and the thermal stability of HBT arrays used in a power amplifier. Shared ballast arrays are shown to be less thermally stable than individually ballasted arrays and thus have more failures during RFHTOL testing. Electro-thermal results indicate the layout aspects of power amplifier module also play an important role in determining junction temperatures for various stages.

A compact high efficiency 8 kW 325 MHz power amplifier for accelerator applications

A solid state RF power amplifier (SSRFPA) has been designed and developed for 8kW RF power at 325MHz. The work was carried out to achieve high efficiency (over 70% efficiency), high gain and compact size for the amplifier module. The sub-components of this amplifier like a 1kW amplifier module at 325MHz, an 8-way RF power combiner rated for 8kW RF power and a micro-strip based power divider have been designed and developed in-house. The size of the amplifier is miniaturized by incorporating innovative design techniques and proper selection of the substrate material in the input/output matching networks. Measured power gain and conversion efficiency of the solid state RF power amplifier module at 1.06kW output is 21.7dB and 73.2%, respectively. A coaxial line based 8-way Wilkinson power combiner has been designed and developed. Return loss of the combiner at the output (combined) port is 26.4dB at 325MHz. Transmission parameters of the combiner from each input (splitting) port to output port are 9.1dB±0.15dB. This amplifier uses a pre-driver of 20W and a driver amplifier of 150W. Total power gain and efficiency of 8kW SSRFPA have been 92.3dB (including the driver stages) and 68.3%, respectively. The harmonic content in the RF output is less than −50dBc for all the harmonics. Main features of this development are high power density (kW/cm3), large value for kW/module, high efficiency (68.3%) for 8kW SSRFPA at 325MHz and rugged operation.

Development of 3 kW at 325 MHz solid-state RF power amplifier using four power amplifier modules

A high power solid-state RF power amplifier of 3kW at 325MHz has been developed using only four RF power amplifier modules of 850W power output each. The design and characterization of RF power modules have been presented. A four way Wilkinson power combiner adds the output of four power amplifier modules with a total transmission loss of less than 6%. The combined power amplifier has a power gain of 20.2dB at 1-dB compression point, and the corresponding output power is 2.8kW at 325MHz. The drain efficiency of the power amplifier is 65.3% at 3kW. All the harmonics of this amplifier are below −40dBc. The amplifier has better characteristics like fewer numbers of active devices per kilo watt, high efficiency, high gain, and ruggedness etc for RF accelerator applications.

A simple and effective load-pull system for RF power transistor large-signal measurements for wireless communication power amplifier design

Conventional load-pull methods for RF power transistor large-signal measurements usually need complicated RF measurement instrumentation. A simple load-pull measurement setup and a test procedure with IEEE-488 GPIB control and data acquisition capability has been developed. This is used to facilitate the design of an RF power amplifier (PA) for wireless communication applications. Compared with the conventional load-pull method, it is simpler and less costly, yet effective. Measured examples of Siemens GaAs FET's CLY-2 and CLY-10, which are used to design a RF PA module for ISM-band (902-928 MHz) wireless communications, are presented.