In this paper, a new low-voltage, MOS-only, third order low-pass filter is proposed. The core circuit consists of only three MOSFETs and their parasitic gate to source capacitances as passive elements. Using TSMC 0.18 mu m technology parameters, the circuit with all biasing elements included consumes just 0.69mW for a cut-off frequency higher than 200MHz under a single supply of 1.8V. Non-ideal effects have been investigated and dynamic threshold voltage MOS (DTMOS) tuning technique has been developed for the filter circuit to suppress the non-idealities. Resulting circuit is capable of operation at high frequencies with low power consumption due to the usage of significantly less number of transistors than conventional active block-based filtering circuits.