A Magnetically Coupled All-Pass Phase Shifter through Heterogeneous Integration

In this work, the concept of heterogeneous integration is adopted to implement an analog phase shifter based on magnetically coupled all-pass network topology. The magnetically coupled all-pass network is composed of coupled inductors and ferroelectric varactors. The coupled inductors are realized using a commercial GaAs-based integrated passive device process, whereas the ferroelectric varactors is fabricated using an in-house process on a sapphire carrier substrate. The implementation of the phase shifter is completed by mounting the GaAs chip on the sapphire carrier through flip-chip bonding. Measurement results show that the phase shifter exhibits a maximum phase shift of 161 degree at 2.35 GHz under 10-V bias. The successful implementation of the phase shifter demonstrates the potential of such heterogeneous integration for realizing tunable RF/microwave circuits.