X band distributed phase shifter based on sol-gel BCTZ varactors

This paper presents the first phase shifter based on sol-gel Barium Calcium Zirconate Titanate (BCTZ) thin ferroelectric film. It is a coplanar waveguide distributed phase shifter with BCTZ varactors used as tuning elements. It presents a continuous phase shift of 285° at 12 GHz (180° at 8 GHz) with a 20 V bias voltage. Its figure of merit is 26°/dB and its return loss is better than 12 dB for the 8 to 12 GHz frequency bandwidth. The presented phase shifter is the only phase shifter based on low cost sol-gel deposition to compete with the best reported X band ferroelectric phase shifters.