Sensor arrangement and method

1. A sensor arrangement, comprising:

a first capacitive sensor having a first terminal coupled to a reference potential;

a second capacitive sensor;

a charge pump coupled to a second terminal of the first capacitive sensor and to a first terminal of the second capacitive sensor, the charge pump being operable to produce a single positive bias voltage relative to the reference potential, and to separately deliver the single positive voltage to each of the first capacitive sensor and to the second capacitive sensor; and

a differential output having a first terminal coupled to the second terminal of the first capacitive sensor and having a second terminal coupled to a second terminal of the second capacitive sensor.

2. The sensor arrangement of claim 1 , wherein the first and the second capacitive sensor are operable to detect the same parameter.

3. The sensor arrangement of claim 2 , wherein the first and the second capacitive sensors are MEMS sensors.

4. The sensor arrangement of claim 1 , wherein a high-pass filter is coupled between the second terminal of the first capacitive sensor and the first terminal of the differential output.

5. The sensor arrangement of claim 1 , wherein the first and the second capacitive sensor have the same geometric orientation.

6. The sensor arrangement of claim 1 , wherein a difference amplifier is coupled to the differential output.

7. The sensor arrangement of claim 6 , wherein an analog-to-digital converter (ADC) is coupled downstream the differential output and a radio frequency filter is coupled between the differential output and the ADC.

8. The sensor arrangement of claim 1 , wherein the charge pump is operable to provide a first positive bias voltage to the first capacitive sensor and a second positive bias voltage to the second capacitive sensor.

9. A sensor interface circuit comprising:

a first voltage bias terminal and a first amplifier input terminal adapted to be coupled to a first capacitive sensor;

a second voltage bias terminal and a second amplifier input terminal adapted to be coupled to a second capacitive sensor;

a first differential output terminal and a second differential output terminal across which a differential output is adapted to be produced;

a first amplifier having an input coupled to the first amplifier input terminal and an output coupled to the first differential output terminal,

a second amplifier having an input coupled to the second amplifier input terminal and an output coupled to the second differential output terminal, and

a charge pump adapted for producing a single positive bias voltage relative to a reference voltage;

wherein the single positive bias voltage produced by the charge pump is separately delivered to each of the first amplifier input terminal and the second voltage bias terminal; and

wherein the first voltage bias terminal is coupled to the reference voltage.

10. A sensor interface circuit in accordance with claim 9 , wherein the input of the first amplifier is coupled to first amplifier input terminal and the positive bias voltage produced by the charge pump via a DC blocking capacitor.

11. A sensor interface circuit in accordance with claim 9 , wherein the positive bias voltage produced by the charge pump is coupled to the first amplifier input terminal, and the second bias voltage terminal via a respective anti-parallel diode.

12. A sensor interface circuit in accordance with claim 9 , wherein the reference voltage is a ground potential.

13. A sensor interface circuit in accordance with claim 9 , wherein the input of the first amplifier and the input of the second amplifier are each associated with a respective defined DC operating point.

14. A sensor interface circuit in accordance with claim 13 , wherein the respective defined DC operating point is associated with a respective feedback loop.

15. A sensor interface circuit in accordance with claim 14 , wherein each of the respective feedback loops includes a low pass filter having an input coupled to a respective one of the outputs of the first and second amplifiers, and an output coupled to a respective one of the inputs of the first and second amplifiers.

16. A sensor interface circuit in accordance with claim 13 , wherein the respective defined DC operating points are each coupled to the respective one of the input of the first amplifier and the input of the second amplifier via a respective anti-parallel diode.

17. A sensor interface circuit in accordance with claim 9 , further comprising:

a first capacitive sensor coupled across the first voltage bias terminal and the first amplifier input terminal; and

a second capacitive sensor coupled across the second voltage bias terminal and the second amplifier input terminal.

18. A method for providing a differential sensor signal, the method comprising:

producing a single positive bias voltage relative to a reference voltage by a charge pump, wherein the single positive bias voltage produced by the charge pump is separately delivered to each of a first amplifier input terminal of a first amplifier and a second voltage bias terminal of a second amplifier, wherein the reference voltage is coupled to a first voltage bias terminal of the first amplifier;

creating a first amplifier output signal in the first amplifier from a voltage detected across the first amplifier input terminal of the first amplifier and the first voltage bias terminal of the first amplifier, which are adapted to be coupled to a first voltage sensor;

creating a second amplifier output signal in the second amplifier from a voltage detected across a second amplifier input terminal of the second amplifier and the second voltage bias terminal of the second amplifier, which are adapted to be coupled to a second voltage sensor; and

providing a differential sensor signal across the first amplifier output signal and the second amplifier output signal.