A pressure sensor apparatus is disclosed. The pressure sensor apparatus includes a bulk acoustic wave (BAW) die having a die interface side and a pressure contact side, a sensor BAW resonator and a reference BAW resonator disposed on the die interface side of the BAW die, a control circuit die coupled to the die interface side of the BAW die via an attachment layer, and an extended opening on the pressure contact side that extends into a depth of the BAW die and is generally aligned with the sensor BAW resonator, the extended opening being configured to translate an external pressure on the pressure contact side onto the sensor BAW resonator.