# Mechanically Modulated Microwave Circulator

## TL;DR

This paper introduces the first MEMS-only microwave circulator using a differential FBAR design that employs mechanical modulation via bending modes, achieving high isolation and low insertion loss at GHz frequencies.

## Contribution

It presents a novel MEMS-only circulator design utilizing differential FBARs with mechanical modulation, eliminating the need for varactors or switches.

## Key findings

- Achieves 61.5 dB isolation at 2.68 GHz
- Insertion loss of 1.8 dB
- Isolation bandwidth of 4.7 MHz at -25 dB

## Abstract

This work presents a differential FBAR circulator that uses the bending mode to mechanically modulate the FBAR mode without any varactors or switches. The differential FBAR circulator achieves a 61.5 dB isolation (IX) with an insertion loss (IL) of 1.8 dB at 2.68 GHz, demonstrating the first MEMS-only circulator. The isolation bandwidth at -25 dB is 4.7 MHz and power handling of the circulator is limited by the FBARs to +34 dBm.

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Source: https://tomesphere.com/paper/1906.05969