Pulse modulator and pulse modulation method
AssigneeLITEF GmbH
InventorGuenter Spahlinger
Life of this patent
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Abstract
A pulse modulator has a subtraction stage that produces a control error signal from the difference between a complex input signal and a feedback signal. A signal conversion stage converts the control error signal to a control signal. The control signal is multiplied by a complex mixing signal at the frequency ω0 in a first multiplication stage. At least one of the real and imaginary parts of the up-mixed control signal is then quantized by a quantization stage to produce a real pulsed signal. The pulsed signal is then employed to produce the feedback signal for the subtraction stage in a feedback unit. The pulse modulator according to the invention allows the range of reduced quantization noise to be shifted toward a desired operating frequency ω0.
Claims22
A drive circuit for a micromechanical resonator, which has at least one pulse modulator for conversion of a complex input signal to a pulsed signal, and which has:
- a subtraction stage which produces a control error signal from the difference between the complex input signal and a feedback signal;
- a signal conversion stage, which converts the control error signal to a control signal;
- a first multiplication stage, which multiplies the control signal by a complex mixing signal oscillating at the frequency ω0, and thus produces at least one of a real part and an imaginary part of a control signal which has been up-mixed by ω0,
- a quantization stage, which quantizes at least one of the real part and imaginary part of the control signal which has been up-mixed by ω0 and thus produces the pulsed signal, with the pulsed signal which is produced by the at least one pulse modulator being used for electrostatic oscillation stimulation of a resonator, and with the pulse modulator being operated at a sampling frequency ωA which is 2 to 1000 times higher than the mixing frequency ω0,
- a feedback unit, which uses the pulsed signal to produce the feedback signal for the subtraction stage,
- said first multiplication stage having a first multiplier for the in-phase signal path and a second multiplier for the quadrature signal path, with the first multiplier multiplying the real part of the control signal by the real part of the complex mixing signal oscillating at the frequency ω0, and thus producing a first result signal, and with the second multiplier multiplying the imaginary part of the control signal by the imaginary part of the complex mixing signal oscillating at the frequency ω0, and thus producing a second result signal;
- and
- the pulse modulator has an adder which adds the first result signal from the first multiplier and the second result signal from the second multiplier to form a sum signal in order to determine the real part of the up-mixed control signal.
A method for pulse modulation of a complex input signal, characterized by the following steps:
- production of a control error signal from the difference between the complex input signal and a feedback signal;
- conversion of the control error signal to a control signal;
- multiplication of the control signal by a complex mixing signal oscillating at the frequency ω0, wherein the real part of the control signal is multiplied by the real part of the complex mixing signal oscillating at the frequency ω0, and a first result signal is thus produced, and the imaginary part of the control signal is multiplied by the imaginary part of the complex mixing signal oscillating at the frequency ω0, and a second result signal is thus produced;
- the first result signal and the second result signal form a sum signal in order to determine the real part of the up-mixed control signal;
- quantization of at least one of the real part and imaginary part of the control signal, up-mixed by ω0, in order to produce a pulsed signal, with the pulsed signal being used for electrostatic oscillation stimulation of a micromechanical resonator, and with the pulse modulation being carried out at a sampling frequency ωA which is 2 to 1000 times higher than the mixing frequency ω0;
- production of the feedback signal from the pulsed signal.
A rotation rate sensor of the type that comprises a drive circuit and a micromechanical resonator, wherein said drive circuit includes at least one pulse modulator for conversion of a complex input signal to a pulsed signal for application to said resonator, said drive circuit further including:
- a subtraction stage which produces a control error signal from the difference between the complex input signal and a feedback signal;
- a signal conversion stage, which converts the control error signal to a control signal by integration;
- a first multiplication stage, which multiplies the control signal by a complex mixing signal oscillating at the frequency ω0, and thus produces at least one of a real part and an imaginary part of a control signal which has been up-mixed by ω0,
- a quantization stage, which quantizes at least one of the real part and imaginary part of the control signal which has been up-mixed by ω0 and thus produces the pulsed signal, with the pulsed signal which is produced by the at least one pulse modulator and which is used for electrostatic oscillation stimulation of the micromechanical resonator, and with the pulse modulator being operated at a sampling frequency ωA which is 2 to 1000 times higher than the mixing frequency ω0, and
- a feedback unit, which uses the pulsed signal to produce the feedback signal for the subtraction stage.
A method for operating a rotation rate sensor of the type in which a micromechanical resonator is driven using pulse modulation of a complex input signal, characterized by the following steps:
- production of a control error signal from the difference between the complex input signal and a feedback signal;
- conversion of the control error signal to a control signal by integration;
- multiplication of the control signal by a complex mixing signal oscillating at the frequency ω0, with at least one of the real part and imaginary part of a control signal, up-mixed by ω0, being produced;
- quantization of at least one of the real part and imaginary part of the control signal, up-mixed by ω0, in order to produce a pulsed signal, with the pulse modulation being carried out at a sampling frequency ωA which is 2 to 1000 times higher than the mixing frequency ω0;
- multiplication of the pulsed signal by a complex mixing signal oscillating at the frequency ω0 to generate the feedback signal from the pulsed signal;
- and
- using the pulsed signal for electrostatic oscillation stimulation of the micromechanical resonator.
Dependencies are inferred from the claim text.