A Miniaturized Monolithic PCM Based Scalable Four-Port RF Switch Unit-Cell

This paper reports the design and fabrication of a miniaturized phase-change material (PCM) germanium telluride (GeTe) based radio-frequency (RF) four-port switch cell. It has two states allowing either straight or cross-connection between the ports. The scalability can be achieved to m×n switch matrix by combining unit-cells. The switch cell is fabricated using a six-layer fabrication process which has two metal layers for RF signal routing. The unit-cell consists of a cross-junction and six RF-PCM series switches, arranged in an order to achieve the desired switch functionality. RF-PCM switches are optimized to achieve high resistance ratio between OFF-state and ON-state (R
_off
/R
_on
). RF performance is simulated and measured, demonstrating an ON-state insertion loss of less than 1.4 dB and OFF-state isolation better than 20 dB over DC-26 GHz for all possible combinations. The proposed PCM switch cell promises to be useful in the realization of multi-band switchable band reject filters.