In this presentation, piezoelectric phononic crystals (PPhC) made up of interdigitated combs of periodic electrodes are considered. In addition to Bragg bandgaps due to the presence of periodic electrodes, their interconnection results in an additional level of electrical periodicity opening supplementary bandgaps in the dispersion curves which correspond to electrical resonance/antiresonance of the comb pairs. The presence of bandgaps is also showcased by calculation of the reflection coefficient of finite size interdigitated comb PPhC for surface acoustic waves on a piezoelectric substrate, revealing the presence of high amplitude reflection coefficient lobes near these bandgap frequencies. Using these mirrors, single port SAW resonators operating around 1.6 GHz are designed to provide experimental verification of the mechanism for bandgap opening and a practical application in an electroacoustic device for signal processing.