Characteristic of the new type BST variable capacitance tested by VCO circuit
Yongjun Tang · Electronic Components and Materials · 2010
Based on the varactor mechanism of the new type BST capacitor,a VCO(voltage controlled oscillator) test circuit was designed using MC12148 integrated chip.Voltage-controlled characteristic of the new type BST was studied through the capacitance value and permittivity of the material,which were calculated by measuring the corresponding frequency of different control voltage.And then a formula about the connection of this BST material’s voltage and capacitance was deduced.The results show that the capacitance of the new BST material can be changed under both positive and negative bias voltage and its maximum withstand voltage is 40 V.Its capacitance tuning rate is 10.691% and voltage-controlled sensitivity is 5.717 kHz/V,which are all very small.The sensitivity and precision of synthesized-frequency can be increased when the material is used in the frequency synthesizer fine tuning.