The design and implementation of a CMOS current- mode fourth-order Butterworth continuous-time leap-frog (LF) multiple loop feedback (MLF) lowpass filter is described. The filter is implemented using a fully-differential linear, low voltage and low power operational transconductance amplifier (OTA). PSpice simulations using a standard TSMC 0.18 mum CMOS process with 1.5 V power supply have shown that the cut-off frequency of the filter ranges from 240 MHz to 300 MHz and dynamic range is about 58 dB at 240 MHz of cut-off frequency. The power consumption of the filter is only from 22.3 to 55 mW. The total output noise density is about 390 nA/VHz.