A filter comprises a shallow bulk acoustic wave (SBAW) longitudinally coupled double mode resonator (LCR) and a reactance coupled between an input and an output of the resonator. Due to its use of a piezoelectric substrate with high electromechanical coupling and an orientation for propagating SBAWs, the resonator has a relatively poor stop band attenuation in a shoulder region on a high frequency side of its pass band. At frequencies in the shoulder region, a signal coupled via the resonator from the input to the output is reduced by a signal of opposite phase coupled via the reactance with a similar attenuation, thereby improving attenuation in the shoulder region. The reactance can be a capacitance formed on the substrate surface.