Apparatus and method for detecting a target environmental variable that employs film-bulk acoustic wave resonator oscillators

A method for detecting a target environmental variable comprising:

• utilizing a first film-bulk acoustic resonator (FBAR) oscillator that includes a first FBAR with a first response to the target environmental variable to generate a first frequency;
• utilizing a second film-bulk acoustic resonator (FBAR) oscillator that includes a second FBAR with a second response to the target environmental variable to generate a second frequency;
• and
• detecting a change in the target environmental variable based on the first frequency and the second frequency.

A method for manufacturing a target environmental variable detecting apparatus comprising:

• forming a first film-bulk acoustic resonator (FBAR) oscillator that has a first response to the target environmental variable to generate a first frequency on a first wafer;
• forming a second film-bulk acoustic resonator (FBAR) oscillator that has a second response to the target environmental variable to generate a second frequency on the first wafer;
• and
• forming a circuit that receives the first frequency and the second frequency and generates a difference frequency that represents the target environmental variable.