The outputs are on the left of the front
panel to accommodate neat cabling to
high voltage amplifiers that typically have
their inputs at the left side too.
Bridge mode
The WMA-IB-HS can be used to double
the maximum output voltage driving a
load, such as a piezo actuator, EO
(electro-optical) modulator, or MEMS
(electromechanical
systems)
device,
among many others. This is achieved by
driving two high voltage amplifiers both
with the same signal, but with opposite
polarity. The outputs of the amplifiers are
connected in bridge mode. Fig. 1 shows
the concept of the bridge mode circuit.
Figure 1. Doubling the maximal output
voltage by using ‘bridge mode’
The WMA-IB-HS inverts the signal and
provides the signal for both amplifiers. The
outputs of the two amplifiers are
connected to the floating, ungrounded
load. The WMA-IB-HS phase inverter -
buffer amplifies 1x. If both amplifiers
amplify e.g. 20x, the total output voltage
across the load will be doubled in bridge
mode, i.e. 40x in this case.
Figure 2. Connecting the high-speed
phase inverter buffer and two amplifiers for
bridge mode operation
Fig. 2 shows an actual setup with the high-
speed phase inverter buffer connected to
two high voltage amplifiers to drive them in
bridge mode.
When two amplifiers are driven in bridge
mode, the high voltage output signal with
twice the amplitude of the individual high
voltage amplifiers is available between the
inner pins of the two high voltage amplifier
BNC outputs and can be connected to the
load (Fig 3). Make sure that the load is not
grounded to the same ground as the
amplifiers, as this would short-circuit one
of the two high voltage amplifiers. This will
not damage the amplifier (if it is short-
circuit proof) but would reduce the output
voltage available to that of a single
amplifier only.
Figure 3. Connecting a load in bridge
mode to two high voltage amplifiers
Connecting the load
The high speed phase inverter - buffer in
combination with two Falco Systems high
voltage amplifiers is capable of both very
high speed and low noise performance.
This performance can only be obtained
with correct shielding of the cables
connecting to the load and, if possible,
shielding of the load itself. Solid BNC
connectors and/or short, high quality BNC
cables are recommended.
Some loads, such as certain EO-
modulators, have a differential connector
available, or two individual connectors, to
drive them differentially (Fig. 4).
-1x
Vin
Amp
Amp
Load
Load
