A 3V-50 MHz analog CMOS current-mode continuous-time active filter with a negative resistance load (NRL) is proposed. In order to design a current-mode current integrator, a modified basic current mirror with a NRL to increase the output resistance is employed. The inherent circuit structure of the designed NRL current integrator, which minimizes the internal circuit nodes and enhances the gain bandwidth product, is capable of making the filter operate at the high frequency. The third order Butterworth low pass filter utilizing the designed NRL current integrator is synthesized and simulated with a 1.5 µm CMOS n-well process. Simulation result shows the cutoff frequency of 50 MHz and power consumption of 2.4mW/pole with a 3V power supply.