Phase-locked loop for a driver circuit for operating a MEMS gyroscope
A phase-locked loop for a driver circuit for operating a MEMS gyroscope, including a seismic mass that is excitable into oscillations. The phase-locked loop including an input interface for receiving position signals that represent the present position of the oscillating seismic mass of the MEMS gyroscope, a phase detector for ascertaining the phase and frequency of the present oscillation movement of the seismic mass, based on the received position signals, at least two oscillators that are alternatively activatable, the alternatively activatable oscillators having different energy consumptions and/or different noise properties, and at least one output interface for outputting a signal that is provided by the oscillator that is presently activated.
1. A phase-locked loop for a driver circuit for operating a MEMS gyroscope, including a seismic mass that is excitable into oscillations, comprising:
an input interface configured to receive position signals that represent a present position of the oscillating seismic mass of the MEMS gyroscope;
a phase detector configured to ascertain a phase and a frequency of a present oscillation movement of the seismic mass, based on the received position signals;
at least two oscillators that are alternatively activatable, the alternatively activatable oscillators having different energy consumptions and/or different noise properties; and
at least one output interface configured to output a signal that is provided by the oscillator that is presently activated.
2. The phase-locked loop as recited in claim 1 , further comprising:
a loop filter configured to apply at least one transfer function, the loop filter including at least two outputs, each output of the outputs of the loop filter being connected to one of the at least two oscillators, and an independent transfer function being associated with each output of the outputs of the loop filter.
3. The phase-locked loop as recited in claim 1 , wherein at least one of the at least two oscillators has a voltage-controlled or current-controlled design.
4. The phase-locked loop as recited in claim 1 , wherein an energy control unit is provided which is configured to activate one of the at least two oscillators and to deactivate the remaining oscillators of the at least two oscillators, and to activate a switch element, so that by actuating the switch element, the activated oscillator is incorporated into a signal path of the phase-locked loop, and the phase-locked loop is thus closed.
5. The phase-locked loop as recited in claim 4 , wherein the activatable switch element includes a multiplexer.
6. The phase-locked loop as recited in claim 1 , wherein at least one frequency divider is situated between outputs of the at least two oscillators and the at least one output interface.
7. The phase-locked loop as recited in claim 6 , further comprising a separate frequency divider associated with each of the oscillators.
8. A circuit arrangement for operating a MEMS gyroscope that includes a seismic mass that is excitable into oscillations, comprising:
a sensing unit that is connected to the MEMS gyroscope, and via which a useful signal of the MEMS gyroscope is providable;
an amplitude control unit configured to output a control signal for exciting and maintaining a defined oscillation movement of the seismic mass of the MEMS gyroscope, based on position signals that represent a present position of the oscillating seismic mass of the MEMS gyroscope;
a phase-locked loop including:
an input interface configured to receive position signals that represent a present position of the oscillating seismic mass of the MEMS gyroscope,
a phase detector configured to ascertain a phase and a frequency of a present oscillation movement of the seismic mass, based on the received position signals,
at least two oscillators that are alternatively activatable, the alternatively activatable oscillators having different energy consumptions and/or different noise properties, and
at least one output interface configured to output a signal that is provided by the oscillator that is presently activated, the at least one output interface of the phase-locked loop being connected to the amplitude control unit; and
an energy control unit connected to the sensing unit, one of multiple predefined operating modes of the MEMS gyroscope being specifiable using the energy control unit, and the energy control unit being configured to activate one of the at least two oscillators and to deactivate the remaining oscillators of the at least two oscillators as a function of the predefined operating mode.
9. The circuit arrangement as recited in claim 8 , wherein the energy control unit is configured to specify, as an operating mode of the MEMS gyroscope, either an active sensing operating mode in which sensor signals are detected and preprocessed, or at least one standby mode in which no sensor signals are detected and/or preprocessed, that oscillator of the at least two oscillators that has lower noise and/or is more frequency-stable being used for the active sensing operating mode, while a more energy-saving oscillator of the at least two oscillators is used for the at least one standby mode.
10. The circuit arrangement as recited in claim 8 , further comprising:
a switch element activatable by the energy control unit in such a way that an output signal of the activated oscillator is supplied to the amplitude control unit, and the phase-locked loop is thus closed.
11. A MEMS gyroscope sensor system, comprising:
a MEMS gyroscope that includes a seismic mass that is excitable into oscillations; and
a circuit arrangement including:
a sensing unit that is connected to the MEMS gyroscope, and via which a useful signal of the MEMS gyroscope is providable;
an amplitude control unit configured to output a control signal for exciting and maintaining a defined oscillation movement of the seismic mass of the MEMS gyroscope, based on position signals that represent a present position of the oscillating seismic mass of the MEMS gyroscope;
a phase-locked loop including:
an input interface configured to receive position signals that represent a present position of the oscillating seismic mass of the MEMS gyroscope,
a phase detector configured to ascertain a phase and a frequency of a present oscillation movement of the seismic mass, based on the received position signals,
at least two oscillators that are alternatively activatable, the alternatively activatable oscillators having different energy consumptions and/or different noise properties, and
at least one output interface configured to output a signal that is provided by the oscillator that is presently activated, the at least one output interface of the phase-locked loop being connected to the amplitude control unit; and
an energy control unit connected to the sensing unit, one of multiple predefined operating modes of the MEMS gyroscope being specifiable using the energy control unit, and the energy control unit being configured to activate one of the at least two oscillators and to deactivate the remaining oscillators of the at least two oscillators as a function of the predefined operating mode;
wherein the MEMS gyroscope is connected on the one hand to an input interface of the sensing unit, and on the other hand to an input interface of the phase-locked loop and to an input interface and an output interface of the amplitude control device.
12. A method for operating a MEMS gyroscope sensor system, including a circuit arrangement for operating a MEMS gyroscope that includes a seismic mass that is excitable into oscillations, the circuit arrangement including:
a sensing unit that is connected to the MEMS gyroscope, and via which a useful signal of the MEMS gyroscope is providable;
an amplitude control unit configured to output a control signal for exciting and maintaining a defined oscillation movement of the seismic mass of the MEMS gyroscope, based on position signals that represent a present position of the oscillating seismic mass of the MEMS gyroscope;
a phase-locked loop including:
an input interface configured to receive position signals that represent a present position of the oscillating seismic mass of the MEMS gyroscope,
a phase detector configured to ascertain a phase and a frequency of a present oscillation movement of the seismic mass, based on the received position signals,
at least two oscillators that are alternatively activatable, the alternatively activatable oscillators having different energy consumptions and/or different noise properties, and
at least one output interface configured to output a signal that is provided by the oscillator that is presently activated, the at least one output interface of the phase-locked loop being connected to the amplitude control unit; and
an energy control unit connected to the sensing unit, one of multiple predefined operating modes of the MEMS gyroscope being specifiable using the energy control unit, and the energy control unit being configured to activate one of the at least two oscillators and to deactivate the remaining oscillators of the at least two oscillators as a function of the predefined operating mode,
the method comprising:
specifying one of at least two predefined operating modes of the MEMS gyroscope sensor system;
activating one of the at least two oscillators of the phase-locked loop as a function of the predefined operating mode, while the remaining oscillators of the at least two oscillators of the phase-locked loop are deactivated.
13. The method as recited in claim 12 , wherein a switchover is made between an active sensing operating mode in which sensor signals are detected and preprocessed, and at least one standby mode in which no sensor signals are detected and/or preprocessed, a lower-noise and/or more frequency-stable oscillator of the at least two oscillators being used for the active sensing operating mode, while a more energy-saving oscillator of the at least two oscillators is used for the at least one standby mode.
14. The method as recited in claim 12 , wherein a switchover between the predefined operating modes of the MEMS gyroscope sensor system is individually initiated.
15. The method as recited in claim 12 , wherein a switchover between the predefined operating modes of the MEMS gyroscope sensor system is automatically initiated with a specifiable frequency.