BAW Filter for space applications at 4.2 GHz

This paper presents a C-band Bulk Acoustic Wave (BAW) filter for space applications. The Solidly Mounted Resonators (SMR) of the filter are based on an Aluminum Nitride (AIN) technology above a Bragg mirror composed of tungsten (W) and silicon dioxide (SiO2). The resonators used to design the filter have a 5.4% electromechanical coupling coefficient at ≈4.2 GHz and their quality factor at the anti-resonance is close to 700. The filter is centered at 4.2 GHz, it has an 83 MHz bandwidth and the minimum insertion loss in the bandwidth is 3.2 dB. Its volume, smaller than 1 mm³, and its mass, less than 1 gram, are drastically reduced compared to technologies commonly used on-board satellites.