Abstract: A positive feedback RC active biquadratic filter circuit comprising a passive input RC section and an active amplification output section having at least one operational amplifier. The RC section has two true resistive T-networks and a true capacitive T-network connected to receive an input signal. The RC section realizes a second order function with a low Q factor. The operational amplifier has a feedback resistive connection from an output thereof to a mid-junction point between each of three capacitances in the capacitive T-network. The capacitive T-network and one of the two resistive T-networks are connected to a positive input of the operational amplifier. The other resistive T-network is connected to a negative input of the operational amplifier.