Falco Systems WMA-02 User manual

USER MANUAL
● High voltage: 20x amplification up to +175V and -175V output voltage
● DC to 13kHz large signal bandwidth and 50kΩ output resistance
● Power supply 24V DC, battery powered operation possible
● No overshoot with capacitive loads: bandwidth changes automatically
to ensure stability
● Short-circuit protected output
About this manual
This user manual is an integral part of the
Falco Systems WMA-02 and WMA-02LF
high voltage amplifier products. Please
read it carefully and pay attention to the
recommendations and instructions for safe
use.
The WMA-02 high voltage
amplifier: general description
The Falco Systems WMA-02 and WMA-
02LF are high voltage amplifiers that run
from an 24V DC power supply and can be
battery powered if required, e.g. for use in
a Faraday cage. Its internal high voltage
generator is inductor-free and hence does
not spread magnetic interference in
sensitive experimental setups. Its large
voltage range makes it an excellent choice
for use with MEMS devices, EO-
modulators, piezo actuator positioning
systems, beam steering components, and
many more.
The amplifiers’ full-power frequency
response has a -3dB corner frequency at
13kHz. The input impedance is 100kΩ and
the output 50kΩ.
The output noise of the WMA-02 is
<3mVrms. For extremely low noise
applications where bandwidth is not an
issue, the dedicated WMA-02LF version is
available. This amplifier contains an output
low pass filter capacitor which reduces the
bandwidth to 50Hz, but makes the noise
drop to 0.1mVrms. This bandwidth-limited
amplifier is ideal for MEMS or piezo
positioning with manual voltage
adjustment requiring extremely low noise.
Falco Systems WMA-02 High Voltage Amplifier DC – 13kHz

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The WMA-02 and 02LF amplifiers contain
an over-voltage protection for daily use in
the laboratory and are long-term short-
circuit proof. The input (indicated “Input”
on the label), output (indicated “Output”)
and DC power supply (Indicated “24V DC
180mA”) connections are all standard
BNC.
The amplification is 20x (fixed). The
amplifiers have an output voltage range of
–175V to +175V. The 24V DC power
supply requirement offers the possibility
for battery powered operation.
Safety
- This product is able to produce over
175V, but the 50kΩ output impedance
limits the current to a rather safe maximum
of 3.5mA. This voltage is painful, but will
not be lethal (under normal circum-
stances). Nevertheless take care. This is a
high voltage unit and safety measures
should be taken accordingly.
- The internal circuitry of the amplifier
operates at high voltage. Only qualified
personnel from Falco Systems should
service it.
- When the amplifier is turned on or off, a
short voltage spike may appear at the
output which may damage circuitry already
connected to it.
- Replace the fuse with 250V 315mAT
5x20mm rated fuses only.
- This product is only suitable for indoor
use in a class II environment (domestic,
light industrial).
- The power supply connected to the
WMA-02/02LF should be double insulated
(class II) or a SELV type (SELV = Safety
Extra Low Voltage, typically a battery).
- The WMA-02/02LF is a class III product.
Do not connect the amplifier to the mains
safety earth. If this is done, the system
becomes a class I apparatus with class III
isolation, which means that the protective
insulation may be inadequate. Doing so
(only under laboratory conditions) is fully
at the users’ risk. Risk of electric shock!
- The WMA-02/02LF should not be used
above 2000m altitude to prevent electrical
breakdown.
- This product should only be cleaned with
a soft, slightly moist cloth. Unplug the
WMA-02/02LF from the DC power before
cleaning.
Input protection
A low-noise amplifier like the WMA-02 or
WMA-02LF can never be made fully
insensitive to input overload conditions, as
this would limit the performance of the
amplifier to an unacceptably low level. The
absolute maximum input voltage is ±15V.
Warning: exceeding this spec may cause
permanent malfunction of the amplifier!
For normal operation, input voltages
should remain in the -8.75V to +8.75V
range, resulting (with an amplification of
20x) in an output voltage swing of more
than -175V to +175V.
Ouput protection
The WMA-02/02LF has been designed to
be fully stable with all capacitive loads. It
has been optimized for its step-response,
but is also a very good linear and sine-
wave amplifier. No significant overshoot
occurs at any capacitive load.
Overloading or short-circuiting this
amplifier will not break down the amplifier,
due to the 50kΩ current limiting resistor
that has been employed at the output.
Although the amplifier cannot be damaged
by a short-circuit condition or capacitive
loading, two situations should be avoided:
- Connecting a charged capacitor.
- Using high inductance values (coils).

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Figure 1. The 10x probe connected for monitoring the output signal
The load
The output impedance of the WMA-
02/02LF is 50kΩ. The amplifier is generally
used for high-impedance applications
where the load is mainly capacitive. This is
the case for MEMS devices, EO-
modulators and piezo actuators alike. It
should be noted that a coaxial cable also
presents a capacitive load of
approximately 100pF/m. The cables and
capacitance that are connected often limit
the maximum usable frequency due to the
first order RC filter formed by the output
resistance of the amplifier and the
connected capacitance.
If output monitoring is required, it is
recommended to connect a 10x
oscilloscope probe to the output. A special
BNC to probe tip connector is usually
supplied with the probe (Fig. 1). However,
you can choose a different way of
connecting the oscilloscope, as long as
you mind the high output voltage. Pieces
of non-coaxial cable in the connection can
cause overshoot in the oscilloscope
reading.
The amplifier is capable of amplifying
above 9kHz, and should not be used for
telecommunication as described in the
R&TTE directive 95/5/EC. To prevent
unwanted radiation all cables should be
kept shorter than 30m.
Noise and offset
The WMA-02 is a low noise amplifier. The
output noise is typically below 3mV rms. If
this is not low enough, the dedicated
version WMA-02LF is available. It provides
less than 0.1mVrms noise: however, the
bandwidth is limited to DC – 50Hz (-3dB)
instead of DC – 20kHz (-3dB).
Power supply
Use a 24V DC power supply with a
continuous output current capability larger
than 200mA. If the power supply has an
adjustable current limit, it should be set at
200mA or higher too. Falco Systems offers
a suitable 24V power supply, for more
details please visit
www.falco-systems.com/products.html
Amplifier characteristics
In the following pages several amplifier
characteristics are shown:
- Frequency response (Fig. 2, 3)
- Square wave response (Fig. 4, 5, 6)
- Influence of a capacitive load on a
square wave output (Fig. 7)
- Triangle & sine response (Fig. 8, 9)
- Noise & offset (Fig. 10, 11)

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Figure 2. Frequency response at 350Vpp output voltage
Figure 3. Frequency response at 200mVpp output voltage
350
300
250
200
150
100
50
0
100101102103104105
WMA-02
WMA-02LF
Amplitude (Vpp)
Frequency (Hz)
WMA-02
WMA-02LF
Amplitude (mVpp)
Frequency (Hz)
200
150
100
50
0
100101102103104105

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Figure 4. 350Vpp 1kHz square wave
Figure 5. Full scale 10kHz square wave
Figure 6. 30mVpp 1kHz small square wave output signal
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0pF
470pF
2.2n
100pF
1nF
10nF
Figure 7. Full-power 1kHz square wave response with different capacitive loading conditions.
The 50kΩ output resistor limits the speed at which the capacitor can be charged.
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Figure 8. Triangle wave 350Vpp 1kHz
Figure 9. Sine wave 350Vpp 1kHz
Figure 10. Noise (less than 15mVpp or, equivalently, less than 5mVrms) and typical offset
(0.8mV) for the WMA-02. The high voltage generator frequency (around 150kHz) contributes
considerable to the overall noise. This measurement was performed with 1m of coaxial cable
connected to the output
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Figure 11. Noise (about 0.3mVpp or, equivalently, less than 0.2mVrms) and typical offset
(0.8mV) for the WMA-02LF
Technical specifications
Amplification: 20x, fixed
Bandwidth: DC – 13kHz @ -3dB large signal bandwidth (DC – 50Hz for WMA-02LF)
Power supply: 24V DC, 180mA, can be battery powered
Output voltage: -175V to +175V
Noise: <3mVrms noise over the full bandwidth typical for the WMA-02; 1.2mV offset typical
Noise: <0.1mVrms noise over the full bandwidth typical for the WMA-02LF, 1.5mV offset
typical
Input impedance: 100kΩ
Output impedance: 50kΩ
Stability: stable with all capacitive and resistive loads, no overshoot > 5%
Fuse: 1x 315mAT 230V
Operating temperature: 10 – 40°C
Storage temperature: 0 – 60°C
Relative humidity: 10 – 90% non-condensing
Maximum usage height: 2000m
Dimensions: 50 x 100 x 26mm excl. BNC connectors
Weight: 300g
Country of origin: The Netherlands
HS code: 8543 70 90
Specifications may be subject to change.
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Harmonized standards
This product complies with the following
harmonized European standards:
Safety: EN61010-1
EMC: EN61326
WEEE and RoHS
Do not dispose of the WMA-02/02LF
amplifier as standard waste, but discard it
at a WEEE electronic waste collection
point. The amplifier has been built in
compliance with the RoHS directive.
Warranty
Falco Systems products are guaranteed
against malfunction due to defects in
materials or workmanship for a period of 1
year from the date on the invoice.
If a malfunction occurs during this period,
the product will be repaired or replaced
without charge. The product will be
returned to the customer free of charge.
The warranty does not apply to:
- Exterior finish or appearance.
- Malfunction of the product resulting from
use or operation in other ways than
specified in the user manual.
- Malfunctioning due to misuse or abuse of
the product.
- Malfunctioning occurring after changes or
repairs have been made by anyone other
than Falco Systems.
To obtain warranty service, inform Falco
Systems via [e-mail]
You will receive support and further
instructions.
Falco Systems will not be liable for any
consequential damages, including, without
limitation, devices or equipment connected
to the product, injury to persons or
property or loss of use. For more details
see the Falco Systems Standard Terms
and Conditions of Sale, which can also be
downloaded on www.falco-systems.com
User manual version
User manual version: 1.11
Date: March 26, 2020
Falco Systems
Falco Systems BV
Remisestraat 1
2225 TH Katwijk aan Zee
Phone: [phone]
Email: [e-mail]
Website: www.falco-systems.com