Measuring device with a micro-electromechanical capacitive sensor

A measuring device with at least one micro-electromechanical capacitive sensor (9a, 9b) comprising electrodes that move toward and away from each other to measure a mechanical deflection of a test mass (2), with a charge integrator comprising an operational amplifier (11) that has at least one amplifier input (13a, 13b) connected to the capacitive sensor (9a, 9b) and at least one amplifier output (15a, 15b) that is fed back via at least one integration capacitor (16a, 16b) to the amplifier input (13a, 13b), wherein:

• the capacitive sensor (9a, 9b) is configured as a differential sensor with a non-inverting first measuring signal output and an inverting second measuring signal output and the operational amplifier (11) is configured as a differential operational amplifier (11) with a non-inverting first amplifier input (13a), an inverting second amplifier input (13b), a non-inverting first amplifier output (15a), and an inverting second amplifier output (15b);
• the first measuring signal output is connected to the first amplifier input (13a) and the second measuring signal output is connected to the second amplifier input (13b);
• the first amplifier output (15a) is fed back via a first integration capacitor (16a) to the second amplifier input (13b) and the second amplifier output (15b) is fed back via a second integration capacitor (16b) to the first amplifier input (13a);
• the first amplifier input (13a) is connected via a first electrical resistor (17a) and the second amplifier input (13b) is connected via a second electrical resistor (17b) to a terminal (18) for an electrical common-mode reference potential;
• the operational amplifier (11) further comprises a first non-inverting auxiliary input (20a) in addition to the first amplifier input (13a) and a second inverting auxiliary input (20b) in addition to the second amplifier input (13b);
• the second amplifier output (15b) is connected to a non-inverting first input terminal (23a) of a low pass (22) and the first amplifier output (15a) is connected to an inverting second input terminal (23b) of the low pass (22);
• and
• a non-inverting first output terminal (24a) of the low pass (22) is connected to the first auxiliary input (20a) and an inverting second output terminal (24b) of the low pass (22) is connected to the second auxiliary input (20b).

A measuring device with at least one micro-electromechanical capacitive sensor (9a, 9b) comprising electrodes that move toward and away from each other to measure a mechanical deflection of a test mass (2), with a charge integrator comprising an operational amplifier (11) that has at least one amplifier input (13a, 13b) connected to the capacitive sensor (9a, 9b) and at least one amplifier output (15a, 15b) that is fed back via at least one integration capacitor (16a, 16b) to the amplifier input (13a, 13b), wherein:

• the capacitive sensor (9a, 9b) is configured as a differential sensor with a non-inverting first measuring signal output and an inverting second measuring signal output and the operational amplifier (11) is configured as a differential operational amplifier (11) with a non-inverting first amplifier input (13a), an inverting second amplifier input (13b), a non-inverting first amplifier output (15a), and an inverting second amplifier output (15b);
• the first measuring signal output is connected to the first amplifier input (13a) and the second measuring signal output is connected to the second amplifier input (13b);
• the first amplifier output (15a) is fed back via a first integration capacitor (16a) to the second amplifier input (13b) and the second amplifier output (15b) is fed back via a second integration capacitor (16b) to the first amplifier input (13a);
• the first amplifier input (13a) is connected via a first electrical resistor (17a) and the second amplifier input (13b) is connected via a second electrical resistor (17b) to a terminal (18) for an electrical common-mode reference potential;
• the operational amplifier (11) further comprises a first non-inverting auxiliary input (20a) in addition to the first amplifier input (13a) and a second inverting auxiliary input (20b) in addition to the second amplifier input (13b);
• the first amplifier output (15a) is connected to a non-inverting first input terminal (23a) of a low pass (22) and the second amplifier output (15b) is connected to an inverting second input terminal (23b) of the low pass;
• and
• an inverting first output terminal (24b) of the low pass (22) is connected to the first auxiliary input (20a) and a non-inverting second output terminal (24a) of the low pass (22) is connected to the second auxiliary input (20b).