Accelerometer having a grounded shield structure

An accelerometer device comprising:

• a substrate;
• a first proof mass coupled to the substrate that includes a first movable electrode electrically coupled to a first fixed electrode having a first potential and is electrically coupled to a second fixed electrode having a second potential;
• and
• a shield structure coupled to the substrate and formed adjacent the first proof mass, wherein the shield structure is electrically coupled to a fixed ground potential;
• and
• a second proof mass coupled to the substrate that includes a second movable electrode that is electrically coupled to a third fixed electrode having a third potential and is electrically coupled to a fourth fixed electrode having a fourth potential, wherein the second proof mass is electrically coupled to the fixed ground potential.

An apparatus comprising:

• a capacitive transducer, the capacitive transducer comprising:
• a substrate;
• a first proof mass coupled to the substrate that includes a first movable electrode that is electrically coupled to a first fixed electrode and is electrically coupled to a second fixed electrode;
• a second proof mass coupled to the substrate that includes a second movable electrode that is electrically coupled to a third fixed electrode and is electrically coupled to a fourth fixed electrode;
• a shield structure coupled to the substrate, the first proof mass, and the second proof mass, wherein the shield structure is electrically coupled to a ground potential;
• an integrated circuit coupled to the first proof mass, second proof mass, and the shield structure, the integrated circuit comprising:
• driver circuitry electrically coupled to the first fixed electrode, the second fixed electrode, the third fixed electrode, and the fourth fixed electrode;
• a voltage source having a reference voltage value coupled to the driver circuitry, wherein the voltage source is configured to amplify the reference voltage value to a maximum voltage value;
• a charge pump electrically coupled to the driver circuitry and the voltage source, wherein the charge pump is configured to generate a voltage opposite in polarity to that of the maximum voltage value;
• and
• a charge-to-voltage amplifier having a first input and a second input, wherein the first input is at a first input potential and electrically coupled to the first movable electrode of the first proof mass, and wherein the second input is at a second input potential and electrically coupled to the second movable electrode of the second proof mass.

A method comprising:

• providing a substrate, a first proof mass coupled to the substrate that includes a first movable electrode that is electrically coupled to a first fixed electrode and a second fixed electrode, a second proof mass coupled to the substrate that includes a second movable electrode that is electrically coupled to a third fixed electrode and to a fourth fixed electrode;
• coupling a shield structure to the substrate, the first proof mass, and the second proof mass;
• electrically coupling the shield structure to a ground potential;
• providing a reference voltage at a voltage source;
• amplifying the reference voltage to a maximum regulated voltage;
• electrically coupling driver circuitry to the first fixed electrode, second fixed electrode, third fixed electrode, and fourth fixed electrode;
• electrically coupling a charge pump to the driver circuitry;
• electrically coupling a charge-to-voltage amplifier having a first input and a second input to the first movable electrode and to the second movable electrode;
• producing, by a charge pump, a voltage opposite to in polarity to the maximum regulated voltage, wherein a difference in a magnitude of the voltage and the magnitude of the maximum regulated voltage is less than twenty percent of the magnitude of the voltage;
• maintaining, by the driver circuitry, a ground potential at the first fixed electrode, the second fixed electrode, the third fixed electrode, and the fourth fixed electrode in a first state;
• applying, by the driver circuitry, a first excitation voltage at the first fixed electrode and the third fixed electrode at the maximum regulated voltage and a second excitation voltage at the second fixed electrode and fourth fixed electrode having a value opposite to in polarity of the first excitation voltage during a second state;
• and
• detecting, by the charge-to-voltage amplifier, a first capacitance at the first movable electrode at the first input of the charge-to-voltage amplifier and a second capacitance at the second movable electrode at the second input of the charge-to-voltage amplifier during the second state.