Resonantly vibrating accelerometer with cross-coupling signal suppression

An apparatus comprising:

• (a) substantially identical first and second vibrating sensors, each vibrating sensor exhibiting a corresponding fundamental vibrational mode and a set of higher-order vibrational modes corresponding to that fundamental vibrational mode, each fundamental and higher-order vibrational mode of each vibrating sensor being characterized by a corresponding fundamental or higher-order resonant mode frequency;
• (b) an excitation-and-detection circuit structured and connected so as to (i) drive the first vibrating sensor at a selected resonant mode frequency f1 thereof, (ii) drive the second vibrating sensor at a selected resonant mode frequency f2 thereof that corresponds to the selected resonant mode frequency of the first vibrating sensor, and (iii) produce an output signal indicative of a difference frequency Δf=f1−f2 and filtered by at least one low-pass filter characterized by a low-pass cut-off frequency fLP that is less than the difference frequency Δf;
• and
• (c) a proof mass connected to the first and second vibrating sensors so that (i) acceleration of the apparatus in a first direction along a sensing axis causes the proof mass to apply a tensile load to the first vibrating sensor and a compressive load to the second vibrating sensor, (ii) acceleration of the apparatus in a second direction along the sensing axis, opposite the first direction, causes the proof mass to apply a compressive load to the first vibrating sensor and a tensile load to the second vibrating sensor, and (iii) the corresponding tensile or compressive loads applied by the proof mass to the first and second vibrating sensors cause the difference frequency Δf=f1−f2 to vary monotonically with acceleration of the apparatus along the sensing axis.