Microelectromechanical Resonant Circulator (MIRC)

INV-17028

 

Conventional circulators are based on magnetic biasing and ferromagnetic materials. Despite their maturity and broad availability, conventional magnetic circulators are largely unattractive for integration, due to their bulky dimensions and the incompatibility of the magnetic materials with IC technology. Alternative approaches for magnet-less non-reciprocity based on linear and periodically time-variant circuits require either large modulation frequencies (similar to or even higher than RF frequency), which unavoidably increases the power consumption, or the use of off-chip inductors that prevent full miniaturization and integration.

 

This invention proposes a fully integrated Microelectromechanical Resonant Circulator (MIRC) capable of achieving high linearity, wide bandwidth, low insertion loss, and high isolation levels. The MIRC exploits the angular-momentum biased circulators relying on highly frequency-selective MEMS devices. This enables the building of extremely high-Q systems while eliminating the need for large inductors affecting the size and performance of previously developed magneto-free circulators. In particular, MIRC relies on resonators and filters using a new class of Aluminum Nitride MEMS CrossSectional Lame’ Mode resonators, dubbed as “Body-Anchored Cross-Sectional Lame’ mode resonators (BA-CLMRs). Such devices rely on anchors at all displacement nodes, thus enabling better heat-flow towards the substrate and, consequently, increasing the linearity achieved by traditional CLMRs. 

The use of AlN BA-CLMRs to replace LC-resonators is proposed to maximize the circulator’s performance in terms of isolation, insertion loss, and bandwidth, while simultaneously meeting the stringent linearity and size requirements for commercial and military applications.

 

- The MIRC enables lower insertion-loss, higher power handling, a higher degree of miniaturization, and lower power consumption than conventional magneto-free circulators based on angular momentum bias.

- The special displacement modal distribution of BA-CLMRs enables the use of more anchors without affecting their electromechanical performance.

- The development of BA-CLMRs enables the achievement of wide-band, high power handling, and highly frequency-selective circulators for integrated telecommunication platforms.

- The use of commutated MEMS filters with high skirt steepness in MIRC enables the adoption of circulators in multi-band RF platforms that recur to frequency duplex multiplex (FDM) to achieve higher spectral efficiency and a large data-rate.

 

- Multi-band radios for commercial and military applications

- Reconfigurable nonreciprocal circuits for integrated computing platforms

 

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