In this study, an ultra low-voltage low-power operational transconductance amplifier (OTA) is proposed. Dynamic Threshold Voltage MOS (DTMOS) transistors are utilized in the design for using very low supply voltages efficiently. The proposed OTA circuit is employed in a fourth-order band-pass filter topology which is used in EEG data processing with the help of SPICE and MATLAB programs. It is found that simulations are in close agreement with the theoretical calculations.