HF Voltage-Controllable Band-Pass Filter Based on Varactor
Sheng Qian Ma, Chang Rong Zhao, Yan Ping Ji · Applied Mechanics and Materials · 2014
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