The linear response of a novel AlxGa1−xAs superlattice electron‐wave interference diode (EWID) is numerically investigated using the time‐dependent Schro¨dinger equation. This device is based on analogies between electromagnetic waves in dielectrics and quantum mechanical electron waves in semiconductors. These analogies provide a basis for a new class of highly functional devices which use above‐band transport. Recent experimental results and theoretical models showed that the EWID has direct current characteristics similar to the resonant tunneling diode. This first quantum mechanical calculation for the EWID alternating current characteristics shows that the device negative differential resistance (NDR) persists up to about 10 THz. By examining three different EWID designs, it is shown that device parameters, such as the number of layers, have a strong effect on high‐frequency performance. The important property of NDR, combined with expected high current densities and possible integration with optoelectronic devices, makes the EWID a good candidate for high speed applications. ©1995 American Institute of Physics.