The invention relates to a reconfigurable continuous FIR filter. The reconfigurable continuous FIR filter includes a delay line including at least two delay elements coupled in cascade. The reconfigurable continuous FIR filter also includes a filter section including at least three gain-phase elements. The filter section also includes a summing circuit having a plurality of inputs at least equal in number to the at least three gain-phase elements and one output. The reconfigurable continuous FIR filter is configured to exhibit a filter transfer function that is reconfigurable in real time. The invention also related to down-converters using the reconfigurable continuous FIR filter. The invention also related to electromagnetic wave receivers using the reconfigurable continuous FIR filter. The invention also relates to a method for reconfigurable real time continuous filtering.