Higher frequencies are being employed in everyday communications as system developers learn to make use of unlicensed millimeter-wave bands. To help with the use of higher available bands in Fifth-Generation (5G) commercial wireless communications systems, Plextek Ltd. has developed a four-channel monolithic-microwave-integrated-circuit (MMIC) amplifier with phase-adjustable channels and bandwidth of 26 to 30 GHz.
The MMIC was fabricated on a commercial 0.15-μm GaAs pseudomorphic-high-electron-mobility-transistor (pHEMT) semiconductor process, and the firm’s plans include housing the device in a low-cost surface-mount-technology (SMT) package for low-volume production. Each channel in the GaAs pHEMT MMIC incorporates a power amplifier (PA) and an independently controllable 4-b phase shifter. The amplifier on each channel runs on a nominal +6-VDC supply.
The phase state of each phase shifter is controlled by a single-ended transistor-transistor-logic (TTL) compatible control line. All the logic required for controlling the phase shifters and the phase states of the four amplifier channels is included on the MMIC. With this level of phase control, the four-channel amplifier is well suited for optimum performance with phased arrays or other antenna elements in which phase must be adjusted.
The use of a 4-b phase shifter for each amplifier channel allows the insertion phase of each channel to be set with 22.5-deg. resolution. The phase error of such circuits is always a concern, and testing and simulations run on this MMIC have shown that the worst-case RMS phase error is about 2.38 deg. at around 27.5 GHz.
Each amplifier channel provides a little more than 20-dB gain from 26 to 30 GHz, with minimal gain variations with frequency. Though still in its early stages of product development, the amplifier MMIC shows great promise for filling the needs of 5G systems.
Plextek RF Integration Plextek Ltd., London Road, Great Chesterford, Essex CB10 1NY, United Kingdom; +44 (0) 1799 533200