Albert-ludwigs-universitat Freiburg

Maximilian Marx

Yiannos Manoli

Daniel De Dorigo

Xavier Cuignet

Stefan Rombach

A method adapts a resonant frequency of a first filter of a closed control loop to a given frequency. The method includes feeding an output signal of a delta sigma modulator of the closed control loop into a frequency adaptation circuit and determining a first noise spectrum of the output signal in a first frequency band and a second noise spectrum of the output signal in a second frequency band. The first frequency band and the second frequency band are arranged symmetrically with respect to the given frequency. The method includes comparing the first noise spectrum with the second noise spectrum, generating an adaptation signal that causes a frequency adaptation of the resonant frequency if the first noise spectrum differs from the second noise spectrum, and outputting the adaptation signal from the frequency adaptation circuit to a control input of the first filter for adapting the resonant frequency.

Method for automatic frequency adaptation of a filter in a closed loop

A method for adjusting the resonance frequency of a loop filter in a delta-sigma modulator includes input of a filter input signal of a loop filter into a frequency adjustment circuit and determination of a noise spectrum of the filter input signal in a first frequency band and a second frequency band. The first frequency band and the second frequency band are arranged symmetrically around the predetermined frequency. The method includes comparison of the noise spectra and creation of an adjustment signal that leads to a frequency adjustment when the noise spectra deviate from one another. The method also includes feedback of the adjustment signal of the frequency adjustment circuit to a control input of the loop filter for setting the filter frequency in response to the comparative result.

Method for automatic frequency adaptation of filters during operation in closed control loops

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.

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Freiburg, Germany

Maximilian Marx