MEMS capacitive sensor

1. A MEMS capacitive sensor comprising:

a capacitor having a variable capacitance, wherein the capacitor comprises a backplate and a membrane being separated from each other by a variable distance, wherein the capacitor is arranged on a substrate;

an output terminal configured to provide an output signal, wherein the output terminal is connected to the backplate;

a bias voltage input terminal configured to apply a bias voltage, wherein the bias voltage input terminal is connected to the membrane, and wherein the bias voltage input terminal is different from the output terminal; and

a supply voltage input terminal configured to apply a supply voltage, wherein the supply voltage input terminal is connected to the substrate,

wherein the supply voltage input terminal is different from the output terminal and the bias voltage input terminal, and

wherein the MEMS capacitive sensor is configured to generate a level of the output signal in dependence on the distance between the membrane and the backplate.

2. The MEMS capacitive sensor as claimed in claim 1 , further comprising a parasitic capacitance located between the membrane and the substrate.

3. The MEMS capacitive sensor as claimed in claim 2 , wherein the parasitic capacitance is coupled to the bias voltage input terminal and the supply voltage input terminal.

4. The MEMS capacitive sensor as claimed in claim 1 , wherein the substrate comprises bulk silicon.

5. The MEMS capacitive sensor as claimed in claim 1 , wherein the MEMS capacitive sensor is a MEMS microphone.

6. An arrangement for amplifying an output signal of a MEMS capacitive sensor, the arrangement comprising:

a capacitor having a variable capacitance, wherein the capacitor comprises a backplate and a membrane being separated from each other by a variable distance, wherein the capacitor is arranged on a substrate;

an output terminal configured to provide an output signal, wherein the output terminal is connected to the backplate, and wherein the MEMS capacitive sensor is configured to generate a level of the output signal in dependence on the distance between the membrane and the backplate;

a bias voltage input terminal configured to apply a bias voltage, wherein the bias voltage input terminal is connected to the membrane, and wherein the bias voltage input terminal is different from the output terminal;

a supply voltage input terminal configured to apply a supply voltage, wherein the supply voltage input terminal is connected to the substrate, wherein the supply voltage input terminal is different from the output terminal and the bias voltage input terminal;

a signal processing circuit having a supply voltage output terminal configured to provide the supply voltage for the MEMS capacitive sensor and a signal output terminal configured to provide an amplified output signal, wherein the supply voltage output terminal of the signal processing circuit is connected to the supply voltage input terminal of the MEMS capacitive sensor,

wherein the signal processing circuit comprises an amplifier configured to amplify the output signal of the MEMS capacitive sensor and to provide the amplified output signal at the signal output terminal of the signal processing circuit, and

wherein the amplifier of the signal processing circuit is arranged between the supply voltage output terminal and a reference terminal configured to apply a reference voltage.

7. The arrangement as claimed in claim 6 ,

wherein the signal processing circuit comprises a signal input terminal configured to receive the output signal of the MEMS capacitive sensor,

wherein the signal input terminal of the signal processing circuit is coupled to the output terminal of the MEMS capacitive sensor,

wherein the amplifier of the signal processing circuit has a control terminal to control the amplifier, and

wherein the control terminal of the amplifier of the signal processing circuit is directly connected to the signal input terminal of the signal processing circuit.

8. The arrangement as claimed in claim 7 , wherein the amplifier of the signal processing circuit comprises a transistor having a gate connection coupled to the control terminal of the amplifier, an input connection coupled to the supply voltage output terminal of the signal processing circuit and an output connection coupled to the reference terminal and the signal output terminal.

9. The arrangement as claimed in claim 8 , wherein the transistor is a PMOS transistor.

10. The arrangement as claimed in claim 6 , wherein the signal processing circuit has a bias voltage output terminal configured to provide the bias voltage for the MEMS capacitive sensor, and wherein the bias voltage output terminal of the signal processing circuit is coupled to the bias voltage terminal of the MEMS capacitive sensor.

11. The arrangement as claimed in claim 10 , wherein the signal processing circuit comprises a capacitor connected between the bias voltage output terminal and the supply voltage output terminal of the signal processing circuit.

12. The arrangement as claimed in claim 11 , wherein the capacitor of the signal processing circuit is connected in parallel to a parasitic capacitance of the MEMS capacitive sensor.

13. The arrangement as claimed in claim 6 , further comprising a parasitic capacitance arranged between the membrane and the substrate, wherein the parasitic capacitance is coupled to the bias voltage input terminal and the supply voltage input terminal.

14. The arrangement as claimed in claim 6 , wherein the substrate comprises bulk silicon.

15. The arrangement as claimed in claim 6 , wherein the MEMS capacitive sensor is a MEMS microphone.