The invention discloses a narrow-band filter with the linearly adjustable
center frequency. The narrow-band filter with the linearly adjustable
center frequency mainly solves the problems that an existing narrow-band filter is small in dynamic input range, and the
center frequency can not be linearly adjusted. The narrow-band filter with the linearly adjustable center frequency comprises a high-pass
capacitor (1), a low-pass
capacitor (2), a
resistive feedback network (3) and two bipolar
transconductance amplifiers (4 and 5), wherein the positive phase input end of the first
amplifier is connected with the output end of the high-pass
capacitor, the output end of the first
amplifier is connected with the positive end of the low-pass capacitor, and the first
amplifier is fed back to the
negative phase input end through the
resistive feedback network, so that a
negative voltage feedback structure is formed; the negative input end of the second amplifier is connected with the output end of the first amplifier, the positive phase input end of the second amplifier is grounded, and the output end of the second amplifier is connected with the positive phase input end of the first amplifier, so that a negative current feedback structure is formed. According to the narrow-band filter with the linearly adjustable center frequency, the dynamic input range of the filter is enlarged through the two bipolar
transconductance amplifiers, a linearly adjustable
transconductance value is provided for the filter, the center frequency can be linearly adjusted, and the narrow-band filter can be used for
infrared receiver circuits.