A broadband DC to 20 GHz 3-bit MEMS digital attenuator

Abstract

A 3-bit microelectromechanical system (MEMS) digital attenuator is designed with 0-20 GHz bandwidth. The attenuation ranges from 0 to 35 dB with 5 dB step. The attenuator, with the coplanar waveguide (CPW), is implemented by surface sacrificial layer technology. The DC-contact MEMS switches with three contact dimples are symmetrically placed around the T type resistor network, making the switches minimum in number and the structure compact. Through the lumped parameter method, the attenuator has good terminal matches in different attenuation states. The test results show that eight different attenuation states are realized within 0-20 GHz. The attenuation deviation is less than ±5%, the insertion loss is less than 1.7 dB and the voltage standing wave rations is less than 1.4 under most of the attenuation states. With the MEMS switches and CPW being adopted, the attenuator has the advantages of higher linearity, lower insertion loss and power consumption. The chip size is about 3.2 mm 2 including the pad.

RF-MEMS for future mobile applications: experimental verification of a reconfigurable 8-bit power attenuator up to 110 GHz

“…neglecting the down-trend that all the configurations exhibit in the low portion of the range, the flatness improves in the range from 15 dB to 2-3 dB, from the worst to the best case, respectively, over a wide range of 40 GHz. This appears to be a good result when compared to the current literature [30,31].…”

“…The latter component selects/ deselects the resistive load of the former, thus changing the overall resistance of the RF line and, in turn, the level of attenuation. A few reconfigurable MEMS-based RF power attenuator designs have already been reported in the literature, although they include a limited number of different configurations (maximum 3-bit) and are for frequencies no higher than 30 GHz [12,[29][30][31]. A microphotograph of the 8-bit RF-MEMS reconfigurable power attenuator discussed in this contribution, is reported in figure 1.…”

A comprehensive overview of recent developments in RF-MEMS technology-based high-performance passive components for applications in the 5G and future telecommunications scenarios

“…With a reduced footprint of 3.2 mm2, [96] offers a structure composed by three equal subunits in series on the main signal line, determining an attenuation of 5, 10, 20 dB respectively. As depicted by the schematic of Figure 8b, each sub-unit is composed by a T-shaped resistive network and two cantilever switches: one switch rules shunt connection to ground, the other allows to bypass the two series resistive loads.…”

Discussion and Demonstration of RF-MEMS Attenuators Design Concepts and Modules for Advanced Beamforming in the Beyond-5G and 6G Scenario—Part 1

“…As an example, eight units comprising series and shunt resistors are placed alternately along the signal line in [31] to form a 256-states device. In some cases [28,32], such units are placed along different branches, selectable by single-pole-double-throw (SPDT) switches, while in others, sections consisting of two selectable RF lines (one attenuated and the other not attenuated) are cascaded [27,33,34].…”

“…The analog and digital devices developed so far find application in multiple frequency bands, with some ranging from DC up to 20 GHz [33,34], and others reaching 40 GHz [32] or 80 GHz [31]. Concerning the number of achievable attenuation states, most of the digital implementations consist in 3-or 4-bit architectures [27,33], while some reach 8 bits [31].…”