Falco Systems WMA-005 User Manual

DC

DC –––– 20

20kHz High Voltage Amplifier WMA

DC DC

kHz High Voltage Amplifier WMA----000005

2020

kHz High Voltage Amplifier WMAkHz High Voltage Amplifier WMA

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www.falco

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05

0505

USER MANUAL

-75V to +75V output

DC to 20kHz at -3dB full

power bandwidth

single power supply 18V –

30V DC, battery power possible

50kΩ output impedance

Stable with all capacitive

loads, generates no overshoot

Short-circuit protected output

For MEMS devices, EO­modulators, PZT (piezo) positioning,
beam steering, ultrasonics, …

About this manual

This user manual is an integral part
of the Falco Systems WMA-005
amplifier product. Please read it
carefully and pay attention to the
recommendations and the
instructions for safe use.

General description

The Falco Systems WMA-005 is a
high voltage amplifier that runs from
an 18 – 30V 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, PZT (piezo)
positioning systems, beam steering
components, and many more.
The amplifiers’ full-power frequency
response has a -3dB corner
frequency at 20kHz. The input
impedance is 100kΩ and the output
50kΩ.

The output noise is at this price level
impressively low at 3mVrms. For
extremely low noise applications
where bandwidth is not an issue, a
dedicated WMA-005LF version is
available that 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.

The WMA-005 contains an over­voltage protection for the daily use
and abuse in the laboratory and is
long-term short-circuit proof. The
input (indicated “Input” on the W MA­005 label), output (indicated
“Output”) and DC power supply
(Indicated “18 – 30V DC 120mA”)
connections are all standard BNC.

The amplification is 20x (fixed). With
a range of –75V to +75V, a –3dB
bandwidth of 20kHz, possibility for
battery powered operation, and
below 3mVrms output noise, this
amplifier will enable many
measurements in different
applications.

Safety

!

- This product is able to produce over
75V, but the 50kΩ output impedance
limits the current to a rather safe
maximum of 1.5mA. Although this
voltage is painful it will under normal
circumstances not be lethal.
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 this
amplifier.

- 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.

- The Falco Systems WMA-005 is
only suitable for indoor use in a class

II environment (domestic, light
industrial).

- The power supply connected to the
WMA-005 should be double
insulated (class II) or a SELV type
(SELV = Safety Extra Low Voltage,
typically a battery).

- The WMA-005 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 W MA-005 should not be used
above 1500m altitude to prevent
electrical breakdown.

- This product should only be
cleaned with a soft, slightly moist
cloth. Unplug the WMA-005 from the
DC power before cleaning.

Input protection

A low-noise amplifier like the WMA­005 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
maximum input voltage is 10V, and
the absolute maximum rating is 15V.
Warning: exceeding this spec may
cause permanent malfunction of the
amplifier and is not covered by the
warranty!
For normal operation, input voltages
should remain in the –3.75V to
+3.75V range, resulting with an

amplification of 20x in an output
voltage swing of more than –75V to
+75V.

Never apply more than +10V (-10V)
to the amplifier input!

Output protection

The WMA-005 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)

The load

The output impedance of the WMA­005 is 50kΩ. The amplifier is
generally used for high-impedance
applications where the load is mainly
capacitive. This is true for MEMS
devices, EO-modulators and PZT's
(piezo’s) alike. It should be noted
that a coaxial cable also presents a
capacitive load of approximately

100pF/m. The cables that are
connected may well limit the
maximum usable frequency.
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, the user can choose a
different way of connecting the
oscilloscope, as long as care is taken
with the high output voltage. Pieces
of non-coaxial cable in the
connection can cause overshoot in
the oscilloscope reading.

Figure 1. The 10x probe connected

for monitoring the output signal

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 leads
should be kept shorter than 30m.

Noise

The WMA-005 is a low noise
amplifier. The output noise is
typically below 3mVrms. If this is not
good enough, a dedicated version
called the WMA-005LF is available

that provides less than 0.1mVrms
noise: however, the bandwidth is
then limited to DC – 50Hz (-3dB)
instead of DC – 20kHz (-3dB).

Amplifier characteristics

In the following pages, several
amplifier characteristics are shown:

- Frequency response (Fig. 2, 3)

- Square wave response (Fig. 4, 5, 6)

- Capacitive load dependency of
square wave output (Fig. 7)

- Triangle and sine response (Fig. 8,

9)

- Noise and offset (Fig. 10, 11)

Amplitude ( Vpp)

140

120

100

80

60

WMA -005LF

40

20

0

10010110210310410

Frequency (Hz)

Figure 2. Frequency response at

150Vpp output voltage

WMA -005

5

Ampli tude (mVpp)

200

150

100

WMA -005LF

50

0

10010110210310410

Frequency (Hz)

WMA -005

5

Figure 3. Frequency response at

200mVpp output voltage

Figure 4. 150Vpp 1kHz square wave

Figure 5. Full scale 10kHz square

wave

Figure 6. 30mVpp 1kHz small square

wave output signal

0pF

100pF

470pF 1nF

2.2nF 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.

Figure 8. Triangle wave 150Vpp

1kHz

Figure 9. Sine wave 150Vpp 1kHz

Figure 10. Noise (less than 10mV

peak-peak or, equivalently, 3mVrms)

and typical offset (-1.1mV) for the

WMA-005. The high voltage

generator frequency (around

150kHz) contributes considerable to

the overall noise. Loading with 1m of

coaxial cable.

Figure 11. Noise (about 0.2mV

peak-peak or, equivalently, less than

0.1mV rms) and typical offset -

1.3mV) for the WMA-005LF. The

offset may change (becomes less)

with the impedance of the driving

voltage source at the input of the

Technical specifications

Amplification:

Amplification:

Amplification: Amplification:

Bandwidth:

Bandwidth:

Bandwidth:Bandwidth:

for WMA-005

Bandwidth:

Bandwidth:

Bandwidth:Bandwidth:

for WMA-005LF

Power supply

Power supply::::

Power supplyPower supply

DC, 120mA max, can be battery
powered

Output voltage:

Output voltage:

Output voltage:Output voltage:

Noise

Noise:

3mVrms noise over the full

NoiseNoise

bandwidth typical for the WMA­005, -1.1mV offset typical

WMA-005.

20x, fixed

DC – 20kHz @ -3dB

DC – 50Hz @ -3dB

single 18 – 30V

-75V to +75V

Noise:

Noise:

<0.1mV rms noise over the

Noise: Noise:

full bandwidth typical for the
WMA-005LF, -1.3mV offset typical

Input

Input impedance:

impedance:

InputInput

impedance: impedance:

Output impedance:

Output impedance:

Output impedance:Output impedance:

Stability:

Stability:

Stability:Stability:

and resistive loads, generates no

overshoot

FFFFuse:

Operating temperature:

Operating temperature:

Operating temperature: Operating temperature:

Storage temperature:

Storage temperature:

Storage temperature:Storage temperature:

Relative humidity:

Relative humidity:

Relative humidity:Relative humidity:

condensing

Dimensions:

Dimensions:

Dimensions: Dimensions:

excl. BNC’s

Weight:

Weight:

Weight:Weight:

Warranty:

Warranty:

Warranty:Warranty:

Country of origin:

Country of origin:

Country of origin:Country of origin:

Specifications are subject to change

Warranty

Falco Systems products are
guaranteed against malfunction due
to defects in materials or
workmanship for a period of 1 year
from the date of shipment.
If such a malfunction occurs during
this period, the product will be
repaired or replaced (at our option)

stable with all capacitive

use:

1x 315mAT 230V

use:use:

300g

1 year

100kΩ

50kΩ

5 – 50°C

0 – 60°C

10 – 90% non-

50 x 100 x 26 mm

The Netherlands

without charge. The product will be
returned to the customer prepaid.
The warranty does not apply to:

- Exterior finish or appearance

- Malfunction resulting from use or
operation of the product other than
as specified in the user manual

- Malfunctioning due to misuse or
abuse of the product

- Malfunctioning occurring any time
after changes or repairs have been
made to the product by anyone other
than Falco Systems.
To obtain warranty service, the
customer must inform Falco Systems
first, and then send the product,
prepaid, to Falco Systems together
with a proof of purchase of the
product in the form of a bill of sale or
receipted invoice.
This warranty explicitly only covers
the product itself. The repair or
replacement including return to the
customer are the only services
provided to the customer in this
respect. 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.
See for more details the Falco
Systems Standard Terms and
Conditions of Sale.

User manual version

User manual version: 1.3
Date: June 8, 2008

Harmonized standards

This product complies with the
following harmonized European
standards:

EMC: EN61326
Safety: EN61010

WEEE

Do not dispose of the WMA-02 and
WMA-02LF as standard waste, but
bring them to a WEEE electronic
waste collection point.

Falco Systems

Falco Systems

Gelderlandplein 75 L
1082 LV Amsterdam
The Netherlands
Tel. [phone]
Fax. [phone]
Email: [e-mail]
http://www.falco-systems.com