PDX Voltage Amplifiers

PDX Voltage Amplifier - Piezo Driver

The PDX voltage amplifiers set a new standard for the bandwidth and power of piezoelectric drives. The exceptional bandwidth with large capacitive loads and the high output current enables a range of new applications not previously possible. The PDX amplifiers are employed in demanding applications such as high-speed physics, video-speed microscopy, precision manufacturing and piezoelectric vibration control.

The PDX amplifiers are available in two output voltage ranges and three peak current ranges. The b variant is designed for general purpose and scanning applications where peak current may last for up to 100ms. The c variant is designed for applications where a large output current is required for a short period of time. The d variant provides up to 10A of current for applications that require fast step changes in voltage.

The PDX amplifiers contain a new technology called Dynamic Current Control. Compared to other amplifiers with fixed current limits, Dynamic Current Control dramatically improves the maximum output current which allows the reproduction of larger amplitude waveforms with higher frequency. In addition to the fast response, the PDX amplifiers are also easy to use and can drive any capacitive load. Other features include: comprehensive overload protection; an external shutdown function; voltage and current monitor outputs; and front-panel bias-voltage adjustment.



Model PDX150 PDX200
Variant b c d b c d
Peak Current 2A 5A 10A 1.5A 5A 10A
OverloadTime 100ms 1ms 100us 100ms 1ms 100us
RMS Current 1.6A 1.1A
Voltage -30V to 150V* -30V to 200V*
Gain 20 V/V
Signal Bandwidth Greater than 80 kHz (1uF Load)
Power Bandwidth 9.5 kHz 7.2 kHz
Offset From 0V to Full-Range with front panel adjustment
Input Differential, Zin = 22 k
Signal Connectors BNC
Output Connector LEMO and 4mm Jack
Load Stable with unlimited capacitive loads
Overload Thermal, current and voltage overload protection
Noise Ultralow noise, < 320 uV RMS
Environment 0 - 40 C (32-104 F), Non-condensing humidity
Enclosure Rugged desktop enclosure. Rack compatible
Dimensions 212.6 x 304.8 x 132.6 mm (w x d x h)
Power Supply 115V or 230V AC (selectable)

Power bandwidth

The power bandwidth is the maximum frequency sine-wave that can be reproduced at full voltage. The b variants of the PDX150 and PDX200 are designed to maximize the power bandwidth in general purpose and scanning applications. With a capacitive load, the maximum frequency sine wave is $$f^{max}=\frac{I_{pk}}{V_{p-p} \pi C}$$ where \(I_{pk}\) is the peak current, and \(V_{p-p}\) is the peak-to-peak voltage. A table of the approximate power bandwidths for a range of capacitive loads is shown below.

100 nF *9.5 kHz *7.2 kHz
300 nF 9.2 kHz *7.2 kHz
1 uF 4.2 kHz 2.3 kHz
3 uF 1.4 kHz 790 Hz
10 uF 424 Hz 230 Hz
30 uF 141 Hz 79 Hz
100 uF 42 Hz 23 Hz

Power Bandwidth versus Load Capacitance

* With very small loads, the power bandwidth is limited by the slew-rate, which is approximately 4.5 V/us. This can be doubled to 8 V/us if necessary.

Also of interest is the maximum amplitude sine-wave that can be delivered to a capacitive load versus frequency. This relationship is plotted below and can be computed for a specific capacitance by using the links above.

PDX Power Bandwidth

Frequency Response

The PDX amplifiers have an extremely wide bandwidth and can tolerate any capacitive load. The frequency response and small-signal bandwidth are described in the following figure and table.

PDX Frequency Response

No Load78 kHz
0.1 uF200 kHz
1.0 uF84 kHz
10 uF27 kHz
100 uF2.7 kHz

Bandwidth versus Load Capacitance

Noise Performance

The PDX amplifiers are low noise devices designed to exceed the requirements of positioning and imaging systems with sub-atomic resolution. The following table lists the output noise voltage versus load capacitance.

CapacitanceBandwidthNoise (RMS)
No Load 78 kHz 300 uV
100 nF 200 kHz 320 uV
1 uF 84 kHz 312 uV
10 uF 27 kHz 280 uV
100 uF 2.7 kHz 167 uV
1000 uF 270 Hz 192 uV

RMS Noise versus Load Capacitance

Signal Conditioning

The differential input circuit eliminates ground-loops and noise resulting from the interconnection of different instruments.


The PDX amplifiers are housed in a desktop enclosure that can be bolted together in a side-by-side configuration. Mounting in a standard 19-inch rack is also possible with the addition of rack-mount handles.


The PDX amplifiers can be customized to meet a range of industrial or scientific requirements. Specific options include:

  • 19-inch rack kit for two amplifiers
  • 19 inch rack kit for a single amplifier