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Driving High Capacitance Piezo Actuators for Nanopositioning: Bridging the Current–Bandwidth–Noise Triad
  • Tim John Joseph ,
  • V Kartik
Tim John Joseph
Indian Institute of Technology Bombay

Corresponding Author:[email protected]

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The piezoelectric stack actuators typically employed in nanopositioning are highly capacitive and, due to their frequency-dependent behaviour, place extreme demands on the drive electronics, especially in high-bandwidth operation. Typical commonly-available amplifiers target purely resistive or negligibly-reactive loads, rendering them unsuitable for such applications. The few commercially-available devices that can drive such actuators are, due to the limitations of conventional power amplification schemes, largely limited in one or more of the following required performance characteristics: wide load-capacitance range, high output current, high power bandwidth, and low output noise. This article presents a battery-based power amplification topology that has the advantage of being able to stably supply high currents at virtually zero noise over large bandwidths, readily bridging the triad of high current, high bandwidth, and low noise. A linear scheme applicable to a wide load-capacitance range, and stable, oscillation-free operation is realized with minimal bandwidth loss by implementing suitable frequency compensation. The system has the added advantage that the voltage and current capacities can be easily scaled up by simply adding more battery cells. The developed prototype demonstrates a significant improvement in performance compared to the state-of-the-art, and simultaneously achieves high power (150 V, 3.30 A rms) and low noise (max. 3.51 mV, 700 kHz bandwidth) for a wide range of loads. The power bandwidth is 5 kHz (1 uF load) while the small-signal bandwidth is 700 kHz.