Pendulum Instruments · Dual-Channel High-Voltage Linear Amplifiers
A400DI
Dual-channel high-voltage amplifier with built-in phase inverter, ±200 V / 150 mA output, for piezo actuators and precision measurement
The A400DI shares its hardware with the A400D; the key difference is the built-in phase inverter. The two channels can output in phase and inverted, so a floating load driven between them sees twice the single-channel swing, up to 800 Vpp, without any increase in supply voltage. It is the most economical way to a large swing, provided the load can float with neither end grounded. Each channel: ×20 gain, ±200 V, 150 mA, 400 V/µs slew rate, DC to 1 MHz at 100 Vpp and 500 kHz at full swing. The one thing to confirm before ordering is whether your load can float.
Overview
The obvious way to put 800 Vpp across a load is a ±400 V amplifier, but differential drive offers another route: two ±200 V channels, one pushing positive and one negative, so the load sees the sum. The A400DI builds the phase inverter in, so no external inverting circuit is needed and the phase relationship between the two outputs is set by the instrument rather than by the wiring. Beyond cost, this helps safety and insulation: either terminal sits at only 200 V to ground, so insulation and clearances are designed for 200 V rather than 400 V. The limitation is equally clear: the load must float, with neither end grounded. Many piezo stacks and transducers float by nature, but if the device housing is earthed or the mounting fixes one side to the frame, differential drive is not usable and a model with a higher output voltage of its own is the better choice. Slew rate is 400 V/µs and bandwidth at full swing is 500 kHz. Leave the inverter unused and it works as an ordinary dual-channel amplifier.
Key specifications
| Gain | ×20 (fixed) |
|---|---|
| Output voltage range | ±200 V (bipolar); up to 800 Vpp in counter-phase mode |
| Max output current | 150 mA (with current-limit protection) |
| Bandwidth | DC to 1 MHz (100 Vpp); DC to 500 kHz (maximum voltage) |
| Slew rate | 400 V/µs |
| Input voltage (nominal) | ±10 V maximum |
| Input impedance | 1 MΩ (30 pF) |
| Output impedance | < 0.1 Ω |
| Channels | 2 (independent channels, shared supply and ground) |
| Mains | 100/110 V or 220/230 V, 50/60 Hz |
| Dimensions (W × H × D) | 257 mm × 102 mm × 262 mm |
| Weight | 4 kg |
Features
800 Vpp without a 400 V supply
Two channels drive a floating load differentially; the swing doubles at lower cost and lower insulation demands than a single higher-voltage unit.
Phase inverter built in
No external inverting circuit; the phase relationship is guaranteed by the instrument, not by the cabling.
Still 200 V to ground
Insulation and clearances are designed for 200 V, less demanding than a true 400 V model.
The load must float
Neither end may be grounded; an earthed housing or a fixture that ties one side down rules this topology out.
Works as a plain dual channel too
With the inverter unused it is two independent ±200 V channels.
Two modes in one unit
Two fully independent high-voltage channels, or counter-phase mode for double the swing, without buying two instruments for two needs.
Typical applications
Precision positioning
Piezo actuator drive and nanopositioning control
On optical tables and precision positioning systems, engineers use the A400DI to raise a ±10 V function generator signal to ±200 V for piezo stack actuators and nanometer displacement control. The counter-phase outputs can be connected straight across the actuator, doubling the effective swing to ±400 V without an external boost stage.
Microdevice testing
Electrical characterization and functional test of MEMS devices
MEMS sensors, micro-actuators and micromirror arrays need accurate high-voltage excitation during development to measure their electrostatic or piezoelectric response. Lab engineers use the two independent A400DI channels to excite the differential electrodes of one MEMS device, then compare phase and amplitude between channels with oscilloscope math to extract the transfer function and nonlinear behavior.
Display devices
Evaluating LCD and OLED drive waveforms
LC modules and OLED devices in materials development or reliability testing need variable-frequency high-voltage AC waveforms to evaluate electro-optical behavior and threshold voltage. The inverter in the A400DI produces a differential drive directly, so a floating device sees the full bipolar voltage, with 1 MHz bandwidth available for fast sweeps of material curves across a wide temperature range.
Options and configuration
Tick the options you need; we collect them into a configuration list and carry it into the quotation form.
Standard equipment (included)
Other models in the series
Service options
Downloads
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