MEMS amplitude modulator and MEMS magnetic field sensor including same
The present invention provides an amplitude modulator, which is disposed in an area through which a magnetic field flows so as to modulate amplitudes, comprising: a substrate; a first driving electrode which receives a first frequency signal and a second frequency signal supplied from the substrate and carries out resonant motion by the magnetic field; and a second driving electrode for receiving the second frequency signal and carries out resonant motion by the first driving electrode and the magnetic field, wherein a modulated signal is generated by modulating the amplitudes of the first and second frequency signals through the resonant motions of the first and second driving electrodes. Therefore, since the signal generated by modulating a carrier signal through mechanical resonance according to the magnetic field is outputted, amplitude modulation can be carried out without a complicated circuit configuration. In addition, since an MEMS device is a single structure that does not include an insulating layer, a single signal is applied to one structure, thereby simplifying driving, and all the driving electrodes of both ends thereof are driven so as to double a change in variable capacitance, thereby improving sensing ability.
1. An amplitude modulator disposed on an area through which a magnetic field flows to modulate an amplitude, the amplitude modulator comprising:
a substrate;
a first driving electrode to receive first and second frequency signals supplied from the substrate and resonate due to the magnetic field; and
a second driving electrode that receives the second frequency signal and carries out resonant motion with the first driving electrode due to the magnetic field,
wherein the first and second frequency signals are amplitude-modulated by the resonant motion of the first and second driving electrodes to generate an amplitude modulated signal, and
wherein the first frequency signal has a frequency equal to physical resonance frequencies of the first and second driving electrodes.
2. The amplitude modulator of claim 1 , wherein the second frequency signal has a frequency greater than a frequency of the first frequency signal.
3. The amplitude modulator of claim 2 , wherein the substrate includes:
a first reference electrode to which the first and second frequency signals are applied,
a second reference electrode to which the second frequency signal is applied,
a first sensing electrode, and
a second sensing electrode to output the modulated signal,
wherein both ends of the first driving electrode are connected to the first reference electrode and the first sensing electrode, respectively, and
both ends of the second driving electrode are connected to the second reference electrode and the second sensing electrode, respectively.
4. The amplitude modulator of claim 3 , wherein the first driving electrode includes:
a first body, and
a first electrode piece protruding along both sides of the first body,
the second driving electrode includes:
a second body, and
a second electrode piece protruding along both sides of the second body, and
the first and second electrode pieces of the first and second driving electrodes are alternately arranged with each other.
5. The amplitude modulator of claim 4 , further comprising elastic units which are formed between ends of the bodies of the first and second driving electrodes and the first and second reference electrodes and between ends of the bodies of the first and second driving electrodes and the first and second sensing electrodes, respectively.
6. An amplitude modulator disposed on an area through which a magnetic field flows to modulate an amplitude, the amplitude modulator comprising:
a substrate;
a first driving electrode to receive first and second frequency signals supplied from the substrate and resonate due to the magnetic field;
a second driving electrode that receives the second frequency signal and carries out resonant motion with the first driving electrode due to the magnetic field; and
a filter to output only the second frequency signal of the first and second frequency signals to the second driving electrode,
wherein the first and second frequency signals are amplitude-modulated by the resonant motion of the first and second driving electrodes to generate an amplitude modulated signal.
7. The amplitude modulator of claim 3 , wherein the first and second sensing electrodes are connected to a ground through an inductor, and
the second sensing electrode outputs the modulated signal through a high-pass filter.
8. The amplitude modulator of claim 7 , wherein the high-pass filter includes a capacitor.
9. The amplitude modulator of claim 1 ,
wherein the substrate includes
a support substrate, and
an electrode layer on the support substrate, and
the first and second driving electrodes are formed of the electrode layer exclusively.
10. The amplitude modulator of claim 1 , wherein the amplitude modulator includes a MEMS device.