The present subject matter relates to devices, systems, and methods that provide a programmable filter response in a wireless frequency division duplex system. In particular, in some embodiments, a tunable diplex filter for such a system includes a first tunable filter in communication between an input node and a first output node, the first tunable filter being tunable to define a first tunable pass band configured to have a minimum pass band insertion loss at frequencies that are higher than a first reject band, and a second tunable filter in communication between the input node and a second output node, the second tunable filter being tunable to define a second tunable pass band configured to have a minimum pass band insertion loss at frequencies that are lower than the first reject band.