This disclosure provides implementations of electromechanical systems resonator structures, devices, apparatus, systems, and related processes. A resonator structure generally includes a first conductive layer with an input electrode, an output electrode, and a ground electrode. The ground electrode is disposed between the input electrode and the output electrode. In some implementations, the second conductive layer includes an input electrode, an output electrode, and a ground electrode. In some other implementations, a second conductive layer includes a pair of ground electrodes and a signal electrode in the form of an input or output electrode disposed between the ground electrodes. A piezoelectric layer is disposed between the first conductive layer and the second conductive layer. Sub-resonators can be defined in different regions of the structure, such that the piezoelectric layer is capable of moving to produce an output signal having frequencies at a first resonant frequency and a second resonant frequency.