A device includes a resonator stack. The resonator stack includes a first chiplet including a first acoustic resonator having a first resonant frequency and a second chiplet including a second acoustic resonator having a second resonant frequency that is different from the first resonant frequency. The device also includes a substrate coupled to the resonator stack, and electrical interconnections between the first chiplet and the second chiplet to provide a conductive path between the first acoustic resonator and the second acoustic resonator.

A method for manufacturing oscillators of a plurality of types including a first oscillator and a second oscillator, the method includes: manufacturing the first oscillator, the manufacturing the first oscillator including a first-oscillator first step of mounting, to a first container, a first resonator element and a first circuit element configured to oscillate the first resonator element to generate a first oscillation signal, and a first-oscillator second step of mounting, to the first container, a second resonator element whose oscillation frequency is controlled based on the first oscillation signal; and manufacturing the second oscillator, the manufacturing the second oscillator including a second-oscillator first step of mounting a third resonator element and a second circuit element to a second container of the same type as the first container, the third resonator element being of the same type as the first resonator element and the second circuit element being of the same type as the first circuit element and being configured to oscillate the third resonator element to generate a second oscillation signal, and a second-oscillator second step of mounting, to the second container, a fourth resonator element whose oscillation frequency is controlled based on the second oscillation signal and whose frequency is different from the frequency of the second resonator element.