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Notes In order to achieve minimumdistortion of the output wave- form, it is important to ensure that the control input ampli- tude is reduced in proportionto the fall-off of the outputvoltage at higher frequencies.Example: The E-503 (E-663)amplifier can drive a 23µF load at 100V peak-to-peak ff . for more infor-mation on controller selection.

Nanopositioning Controllers - 13949 Typical PI 4-Quadrant Piezo Amplifiers /Position Servo-Controllers

ff . for more in-formation.Therefore the frequency re-sponse graphs actually reflecta much higher load to the am- plifier than a standard capaci- tor of the same value would represent. See p. 2-6 Power Requirements forPiezo (PZT) Operation The frequency response of agiven amplifier depends on the amplifier power, the ampli-fier design, and of course, thePZT capacitance. For dynamic applications, PZTs require high charge and discharge currents. Those requirements are best met by power ampli- fiers that can source and sink high peak currents. The aver- age current is of secondaryimportance. For exact infor-mation on maximum operat- ing frequency with a given PZT load refer to the individ- ual frequency response graphs. Open-loop frequency re-sponse data for all PI PZT power amplifiers in this cata- log were taken after 15 min- utes of continuous operation (PZT and amplifier) at roomtemperature. At power up,(cold conditions) maximum operating frequency is higher. The indicated capacitance val-ues are small-signal values foractual piezo actuators (meas-ured at 1 V, 1000 Hz, 20 °C, no load). The capacitance of piezo ceramics changes significantly with amplitude, temperature, and load, up to approximately 200% of the unloaded small-signal capacitance at roomtemperature. See “Tutorial”, see page 4-27 (sinewave) up to approximately 15Hz. At higher frequencies the output voltage drops off, e.g. to 80V at 20Hz. Therefore it would be important toreduce the input voltageamplitude to 8V (gain=10) at this frequency. Otherwise the amplifier will output a clipped distorted sinewave.
The diagram shows how the LVPZT amplifier input range can be varied with the DC-offset potentiometer. This principle is also valid for HVPZT amplifiers, where the typical input range is 0 to +10V and the output range is 0 to -1000V. The DC-offset potentiometer allows for continuous shifting of the input range between 0V to +10V and -10V to 0V. PZT amplifiers without position servo-control work according to the top branch of the diagram. The slew rate adjustment, servo ON/OFF switch and overflow indicator are only found on position servo-controllers. Note that the DC offset is added to the input voltage before it is amplified. © PI 1998-2005. Subject to change w/o notice. Cat 118 05/09.17 6-52