NON-ADJUSTMENT BANDPASS FILTER APPARATUS

摘要

A controlless band pass filtering system is disclosed. The controlless band pass filtering system comprises: a band pass filter(11) for passing the predetermined band frequency; a peak detector(12) for providing a DC voltage in proportion to the peak value of the output frequency of the band pass filter; a VCO(Voltage Controlled Oscillator)(13) for providing a center frequency corresponding to the DC voltage from the peak detector; a frequency determination unit(14) for comparing the center frequency from the VCO to a required center frequency and for providing a control frequency so as to obtain the center frequency; a V-I converter(16) for converting the voltage of the control frequency from the frequency determination unit to a current; and a capacitor for controlling the frequency band of the band pass filter by charging and discharging according to the output from the V-I converter.