Reconfigurable and Scalable Monolithic Band Reject Circuit Utilizing Phase-Change Switch Matrices

This paper reports a reconfigurable band reject circuit utilizing a chalcogenide phase change material (PCM) germanium telluride (GeTe) based switch matrix. A highly miniaturized and scalable 2×2 switch matrix is developed in-house using a custom eight-layer microfabrication process, including a thermally conductive dielectric for efficient thermal energy transportation. As a proof-of-concept, two band-rejection notch filters are monolithically integrated with the 2×2 switch matrix to demonstrate a reconfigurable 2-bit band reject circuit. The fully integrated circuit is designed with overall device core footprints under 0.68 mm
²
. The circuit does not consume any static dc power consumption and offers non-volatile operation. The circuit is reconfigurable to either reject f
1
at 2.6 GHz, f
2
at 5.8 GHz, both f
1
+ f
2
or bypass the notch filters. The proposed circuit exhibits a measured insertion loss of less than 2.2 dB and a return loss of better than 17 dB. The approach is scalable to a larger number of reconfigurable bands rejection using the 2×2 unit-cell in an upscaled switch matrix.