Papers by Keyword: Varactor

Abstract: Varactor to replace commonly variable capacitance is applied to the tuner. This paper presents the voltage-controllable band-pass filter design method. The filter constitutes of operational amplifier, resistors, varactor MV209 and parallel LC resonant circuit. Center frequency range of the band-pass filters is from 19MHz to 25MHz controlled with DC voltage. It derives the transfer function of the filter and function expression of junction capacitance with reverse voltage. The frequency response of filter simulation and experimental results are given. Key words: Varactor; Band-Pass Filter; Voltage-Controllable Filter; Junction Capacitance

Abstract: A multi-components multi-layer co-fired ceramic varactor with superior performance is here presented. The concept combines a tunable capacitor with optimized properties in a restricted temperature range with PTCR layers to control the overall device temperature. Different prototypes are produced as demonstrator units; one of them is described in detail. The device may be tuned by a primary bias voltage applied to the capacitor and by a secondary voltage applied to the PTCR to set the working temperature. By proper choice of materials, bias voltage and working temperature, the varactor is optimized to the requested figure of merit for a specific application. The prototype here described has shown a tunability >83% @ 2.75 V//m (Patent Pending)

Abstract: Cubic pyrochlore bismuth zinc niobate thin films are known to exhibit voltage dependent dielectric properties. In this paper, we are demonstrating the fabrication and characterization of interdigital (IDC) and circular patch (CPC) capacitors using the pulsed laser deposited Bi1.5Zn1.0Nb1.5O7 (BZN) thin films on sapphire and platinised silicon substrates respectively. The IDCs fabricated are having 12 fingers of width 12 m each and separated by a gap of 8 m. The CPC are having circular patches with inner radius of 100 m and concentric ground plane with a radius of 300m. The electrical properties of these capacitors were characterized both at low frequencies and at microwave frequencies. The CPC varactors were having a tunability of 25% at 15 Volts. The calculated capacitance of the IDC varactor at 5.3 GHz with 0 V dc bias was 1.1 pF, which has got changed to 0.99 pF by the application of 30 Volts exhibiting a tunability of 10%.