Capacitive Instrumentation and Sensor Fusion for High-Bandwidth Nanopositioning

Precision capacitive sensing methods encode the measurement in a high frequency signal, which requires demodulation. To extract the measurement, the signal is observed over many cycles limiting the bandwidth of the sensor and introducing an undesirable phase lag. To address this limitation, this article outlines a design, which fuses the output of a standard modulated capacitive sensor and a charge amplifier, providing an instantaneous capacitive measurement whose bandwidth is only limited by the speed at which the electronics operate.