Novel Aharonov–Bohm type electron interferometers are proposed, which have no curved electron waveguide structures to form a ring geometry. But instead the ring geometry is effectively constructed in astraightdouble quantum well structure, by the control of the shapes of the wave functions by electric fields. The interferometer has a perfect single‐mode channel in each arm of the interferometer as well as the exact 1:1 branching ratio to the two arms, for each electron moving in the plane of the ring.