An inertial sensor, comprising: - a first proof mass configured to oscillate along a sensing axis; - a first tuning electrode and a second tuning electrode forming first and, respectively, second capacitors with the first proof mass, the capacitances of which undergo opposite variations with the oscillation of the first proof mass along the sensing axis; - a second proof mass configured to oscillate along the sensing axis; - a third tuning electrode and a fourth tuning electrode forming third and, respectively, fourth capacitors with the second proof mass, the capacitances of which undergo opposite variations with the oscillation of the second proof mass along the sensing axis; - a driving assembly (14a, 14b, 18a, 18b) coupled to the first and second proof masses (6, 8), configured to cause an antiphase oscillation of the first and second proof mass (6, 8) at a resonance frequency along the sensing axis; - a biasing circuit (49, 51) configured to bias, in a first time interval, the first tuning electrode and the third tuning electrode to generate an electrostatic field which causes a first variation of said resonance frequency; and configured to bias, in a second time interval, the second tuning electrode and the fourth tuning electrode to generate an electrostatic field which causes a second variation of said resonance frequency; and - a sensing assembly (16a, 16b, 20a, 20b, 40, 59, 61), configured to generate an output signal which is a function of a difference between a value of the resonance frequency during the first time interval and a value of the resonance frequency during the second time interval. - a first proof mass configured to oscillate along a sensing axis; - a first tuning electrode and a second tuning electrode forming first and, respectively, second capacitors with the first proof mass, the capacitances of which undergo opposite variations with the oscillation of the first proof mass along the sensing axis; - a second proof mass configured to oscillate along the sensing axis; - a third tuning electrode and a fourth tuning electrode forming third and, respectively, fourth capacitors with the second proof mass, the capacitances of which undergo opposite variations with the oscillation of the second proof mass along the sensing axis; - a driving assembly (14a, 14b, 18a, 18b) coupled to the first and second proof masses (6, 8), configured to cause an antiphase oscillation of the first and second proof mass (6, 8) at a resonance frequency along the sensing axis; - a biasing circuit (49, 51) configured to bias, in a first time interval, the first tuning electrode and the third tuning electrode to generate an electrostatic field which causes a first variation of said resonance frequency; and configured to bias, in a second time interval, the second tuning electrode and the fourth tuning electrode to generate an electrostatic field which causes a second variation of said resonance frequency; and - a sensing assembly (16a, 16b, 20a, 20b, 40, 59, 61), configured to generate an output signal which is a function of a difference between a value of the resonance frequency during the first time interval and a value of the resonance frequency during the second time interval.