A complex filter synthesized from the leapfrog lowpass prototype is proposed. The filter has low sensitivity and, therefore, an improved stability. The tuning system, which is easy to design and well controlled, can be turned off on the completion of tuning, which reduces power consumption and interference with the filter. Implemented in 0. 18 μm CMOS process, the filter is centered at 4 MHz with a bandwidth of 2 MHz and a voltage gain of about 0 dB. The image rejection ratio of the filter is up to 53 dB and its tuning accuracy is about 3%. The device consumes 7.5 mW of Dower.