A circuit for activating a capacitive MEMS structure is provided, with the capacitive MEMS structure having an oscillator element and an electrostatic excitation unit with a first input connection and a second input connection. The circuit includes a high voltage generator, a first pump capacitor, a second pump capacitor, a control unit, and a low voltage operation amplifier. The high voltage generator generates a high voltage and connects to the first input connection and the second input connection. The first pump capacitor is connected to the high voltage generator and includes a first connection connected to the first input connection. The second pump capacitor connects to the high voltage generator and includes a first connection connected to the second input connection. The control unit connects to a second connection of the first pump capacitor and a second connection of the second pump capacitor. The low voltage operation amplifier connects to the control unit.

A velocity calculation device includes: a vertical direction acceleration detection portion that is mounted on a vehicle and detects an acceleration in a vertical direction generated correspondingly to undulation of a road surface; a horizontal direction angular velocity detection portion that is mounted on the vehicle and detects an angular velocity about a horizontal axis orthogonal to a travel direction of the vehicle generated correspondingly to the undulation of the road surface; and a velocity calculation portion that calculates a velocity in the travel direction of the vehicle on the basis of the acceleration in the vertical direction and the angular velocity about the horizontal axis.

A velocity calculation device includes: a vertical direction acceleration detection portion that is mounted on a vehicle and detects an acceleration in a vertical direction generated correspondingly to undulation of a road surface; a horizontal direction angular velocity detection portion that is mounted on the vehicle and detects an angular velocity about a horizontal axis orthogonal to a travel direction of the vehicle generated correspondingly to the undulation of the road surface; and a velocity calculation portion that calculates a velocity in the travel direction of the vehicle on the basis of the acceleration in the vertical direction and the angular velocity about the horizontal axis.