Tunable voltage-controlled oscillator (VCO) with high dielectric constant BCTZ capacitors

This paper presents a voltage-controlled oscillator (VCO) where the resonant circuit consists of a high dielectric constant Ba0.96Ca0.04Ti0.84 Zr-0.16 O-3 (BCTZ) tunable capacitor and an inductor. The tunable capacitors are fabricated by spin-on MOD on SiO 2 /Si substrate with titanium/platinum as the bottom electrode and platinum as the top electrode. The tunability of the capacitors annealed at a temperature 800degreesC to 900degreesC is 35% for an applied voltage of +/-3 volts. Low frequency VCOs built with discrete bipolar junction transistors (BJTs), MOSFETs, inductors and high dielectric tunable capacitors shows a frequency tuning range from 2.52 MHz to 2.32 MHz for an applied tuning voltage of -3 V to 0 V and for a power supply voltage of +3 V.