Memory effects in ferroelectric thick film varactors based on Barium Strontium Titanate

Low cost planar ferroelectric thick film varactors based on Barium Strontium Titanate (BST) are realized and their nonlinear behavior with varying DC bias is investigated. A model for the capacitance tunability is utilized for nonlinear simulations and compared to measurements. The model based on static measurement of the varactor´s capacity is extended by the results from measurements with pulsed tuning voltage. A memory effect in the capacitance tunability of the varactor is observed in measurements with pulsed bias voltage. The impact of this memory effect to the nonlinear properties is presented.