Method for compensating for quadrature
A method for compensating for the quadrature of a micromechanical structure, the micromechanical structure having a substrate having a main extension plane, a seismic mass that is attached by spring elements to the substrate, and first and second compensation electrodes anchored to the substrate; in response to application of a first quadrature voltage between the first compensation electrode and the seismic mass, a first compensation force being produced on the seismic mass and, in response to application of a second quadrature voltage between the second compensation electrode and the seismic mass, a second compensation force being produced on the seismic mass and, in addition, the second quadrature voltage being adjusted as a function of the first quadrature voltage.
1. A method for compensating for a quadrature of a micromechanical structure, the micromechanical structure having a substrate having a main extension plane, a seismic mass that is attached by spring elements to the substrate, and first and second compensation electrodes anchored to the substrate, the method comprising:
in response to an application of a first quadrature voltage between the first compensation electrode and the seismic mass, producing a first compensation force on the seismic mass;
in response to an application of a second quadrature voltage between the second compensation electrode and the seismic mass, producing a second compensation force on the seismic mass; and
adjusting the second quadrature voltage as a function of the first quadrature voltage.
2. The method according to claim 1 , wherein the second quadrature voltage is adjusted in a clocked cycle or continuously as a function of the first quadrature voltage.
3. The method according to claim 1 , wherein the second quadrature voltage is adjusted in such a way that a sum of a square of the first quadrature voltage and a square of the second quadrature voltage is substantially always constant.
4. The method according to claim 1 , wherein the second quadrature voltage is calculated as a function of the first quadrature voltage, the function decreasing monotonically at least between a minimum voltage of the first quadrature voltage and a maximum voltage of the first quadrature voltage.
5. The method according to claim 1 , wherein the second quadrature voltage is adjusted as a function of a root function of the first quadrature voltage.
6. The method according to claim 5 , wherein an argument of the root function is calculated at least as a difference between a square of a first constant and a square of the first quadrature voltage, the first constant including a maximum voltage.
7. The method according to claim 5 , wherein an argument of the root function is calculated from a sum of a square of a first summand, a square of a second summand, and of a square of a third summand, the first summand including a difference between a maximum voltage and an offset voltage, the second summand including a difference between a minimum voltage and the offset voltage, and the third summand including a difference between the first quadrature voltage and the offset voltage, the root function being added to the offset voltage.
8. The method according to claim 1 , wherein the first compensation force produces a first compensating motion of the seismic mass along a compensation direction, and the second compensation force produces a second compensating motion of the seismic mass in a direction that is substantially antiparallel to the compensation direction, the compensation direction being oriented perpendicularly or in parallel to the main extension plane.
9. The method according to claim 1 , wherein the method is used to adjust a micromechanical rotation-rate sensor.