Monolithically Integrated RF-MEMS for Beamforming Applications: A Multi-functional Module with Both Amplitude and Phase Control

The significant data rates associated with current and forthcoming telecommunication standards depend on access points functioning within the millimeter-wave (mmWave) frequency bands, which are distinguished by their antenna array configurations. The anticipated increase in Small Cells (SC) deployment raises concerns about the power consumption of these numerous nodes, thereby rekindling interest in passive electronic solutions for the development of hardware beamforming (BF) architectures. In this regard, the low power requirements, combined with the exceptional and broadband electrical characteristics of Radio Frequency Micro Electro-Mechanical Systems (RF-MEMS), present a viable option for the creation of future reconfigurable BF architectures. This paper illustrates this potential through a monolithic general-purpose module that includes a 3-bit attenuator, three phase-shifting cells, and a switch, all within a compact footprint of 3.36 × 9.51 mm2. The low driving voltage for this network is achieved through the use of movable membranes with meandered beams, which require an actuation voltage of 7 V. Preliminary simulations indicate wideband isolation performance ranging from −25 dB up to −27.22 GHz, alongside amplitude control from −5.39 to −13.51 dB and phase control from 14.03° to 158.46° at the center frequency of 25.87 GHz within the examined spectrum.