Title :
Application of RF Varactor Using BaxSr1-xTiO3/TiO2/HR-Si Substrate for Reconfigurable Radio
Author :
Kim, Ki-Byoung ; Park, Chul-Soon
Author_Institution :
Inf. & Commun. Univ., Daejeon
Abstract :
In this paper, the potential feasibility of integrating BaxSr1-xTiO3 (BST) films into Si wafer by adopting tunable interdigital capacitor (IDC) with TiO2 thin film buffer layer and a RF tunable active bandpass filter (BPF) using BST based capacitor are proposed. TiO2 as a buffer layer is grown onto Si substrate by atomic layer deposition (ALD) and the interdigital capacitor on BST(500 nm)/TiO2(50 nm)/HR-Si is fabricated. BST interdigital tunable capacitor integrated on HR-Si substrate with high tunability and low loss tangent are characterized for their microwave performances. BST/TiO2/HR-Si IDC shows much enhanced tunability values of 40% and commutation quality factor (CQF) of 56.71. A resonator consists of an active capacitance circuit together with a BST varactor. The active capacitor is made of a field effect transistor (FET) that exhibits negative resistance as well as capacitance. The measured second order active BPF shows bandwidth of 110 MHz, insertion loss of about 1 dB at the 1.81 GHz center frequency and tuning frequency of 230 MHz (1.81-2.04 GHz).
Keywords :
atomic layer deposition; band-pass filters; barium compounds; buffer layers; elemental semiconductors; ferroelectric capacitors; field effect transistors; negative resistance; resonators; semiconductor thin films; silicon; software radio; strontium compounds; titanium compounds; varactors; wide band gap semiconductors; ALD; BPF; BST films; BaxSr1-xTiO3-TiO2-Si - Interface; BaSrTiO3-TiO2-Si; CQF; FET; IDC; RF varactor application; Si; Si - Surface; active capacitance circuit; atomic layer deposition; bandwidth 110 MHz; commutation quality factor; field effect transistor; frequency 1.81 GHz; frequency 1.81 GHz to 2.04 GHz; frequency 230 MHz; loss 1 dB; low loss tangent; microwave performances; negative resistance; reconfigurable radio; resonator; silicon wafer; size 50 nm; size 500 nm; thin film buffer layer; tunable active bandpass filter; tunable interdigital capacitor; Band pass filters; Binary search trees; Buffer layers; Capacitance; Capacitors; Radio frequency; Strontium; Substrates; Tunable circuits and devices; Varactors;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2007.527