Nested Miller Compensation Based Op-Amp Design for Piezoelectric Actuators

Dincer Gokcen,Mehmet Akif Çeli̇k,Fatih Emre Aydos

doi:10.17694/bajece.585798

Dincer Gokcen, Mehmet Akif Çeli̇k + Show 1 more

Open Access

https://doi.org/10.17694/bajece.585798

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Abstract

This study introduces the design of a practical three-stage operational amplifier (op-amp) using nested Miller compensation, particularly for piezoelectric actuators. Driving a piezoelectric actuator represents a challenge in amplifier design due to its large capacitive nature. A stable piezo driver needs to be free of oscillations and phase lag. Direct feedback compensation using a conventional Miller capacitor is an effective method as long as the capacitance of the load is considerably close to the value of the Miller capacitor. However, using a large capacitor causes a decrease in the slew rate and gain bandwidth. To avoid this, our design focused on the utilization of nested Miller compensation technique. A prototype of the design working at 100V peak to peak voltage (Vpp) is implemented using commercial off-the-shelf (COTS) components. The measurements show the successful driving capability and step-response of the op-amp design. In the design, Widlar current source is also utilized for thermal stability and short circuit protection. According to simulation results, the proposed op-amp has a slew rate of 0.5 V/μs, an open loop gain of 90dB with 3MHz Gain Bandwidth Product (GBP) and phase margin of 77°, and a common mode rejection ratio (CMRR) of 62dB.

Highlights

THE WIDESPREAD use of piezoelectric actuators in diverse applications stimulate significant research efforts https://orcid.org/ 0000-0003-1847-1356https://orcid.org/ 0000-001-5119-8705https://orcid.org/ 0000-0002-6726-4567Manuscript received July 02, 2019; accepted March 13, 2020
This study introduces the design of a practical three-stage operational amplifier using nested Miller compensation, for piezoelectric actuators
For the development of piezo drivers with high linearity and low-cost [1,2,3]. Due to their unique capability to make displacement in nanoscale, piezo materials are widely used in many scientific applications including atomic force microscopy (AFM), scanning tunneling microscopy (STM), nano- and micromanipulators, and optical microscopy stages [4,5,6]

Summary

Introduction

THE WIDESPREAD use of piezoelectric actuators in diverse applications stimulate significant research efforts https://orcid.org/ 0000-0003-1847-1356https://orcid.org/ 0000-001-5119-8705https://orcid.org/ 0000-0002-6726-4567Manuscript received July 02, 2019; accepted March 13, 2020. Due to their unique capability to make displacement in nanoscale, piezo materials are widely used in many scientific applications including atomic force microscopy (AFM), scanning tunneling microscopy (STM), nano- and micromanipulators, and optical microscopy stages [4,5,6]. In piezoelectric materials, mechanical resonances appear at the frequency range varying from kHz to MHz [11]. This implies that the instability in op-amp operation can induce oscillations at high frequencies and this phenomenon may trigger undesired mechanical resonance

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