The present invention provides tunable film bulk acoustic resonators (FBARs) with the resonant frequency of the acoustic wave to be excited and to be transmitted tuned by digital to analog converters which convert an input digital signal to an output DC voltage and provide DC bias voltages to the FBARs through integrated thin film biasing resistors. The polarity and the value of the output DC voltage are controlled by the input digital signal to achieve selection and tuning of the resonant frequency of the FBARs. A plurality of the tunable FBARs are connected to form microwave filters with tunable bandpass frequencies and oscillators with selectable resonating frequencies by varying the input digital signals applied to the digital to analog converters.