An active module using a ferroelectric CPW phase shifter for a Ku-band APAA system

Abstract

This paper presents the development of an active module using a ferroelectric coplanar waveguide (CPW) phase shifter for a Ku-band active phased array antenna (APAA). This active module performs roles such as amplifying an RF signal with low noise coming from an antenna and changing the phase of a received RF signal. This module is composed of a 3-stage low-noise amplifier (LNA), a high-voltage dc block with an RF choke (RFC), and a ferroelectric phase shifter, whose structure is a CPW transmission line based on a (Ba, Sr)TiO3 (BST) thin film. The ferroelectric BST thin film is deposited on an MgO substrate by using pulsed laser deposition. Both ends of the CPW are continuously tapered to obtain good impedance matching without degrading the phase tuning property of the ferroelectric CPW phase shifter. The active module using a ferroclectric CPW phase shifter attains a phase-controllable range of 360 degrees while retaining a return loss of better than -15 dB at Ku-band. The measured gain of the active module increases from 2 dB to 16 dB corresponding to a change in the dc voltage from 0 to 150 V with a 3.6 dB maximum noise figure at 12 GHz.