Pendulum Instruments · Dual-Channel High-Voltage Linear Amplifiers
A800DI
Dual-channel ±400 V high-voltage linear amplifier with built-in phase inverter, up to 1600 Vpp differential
The A800DI is the top of this line for swing: two ±400 V channels plus a built-in phase inverter reach 1600 Vpp across one floating load. Getting that swing differentially is more practical, in cost and in insulation design, than a single ±800 V amplifier, because either terminal still sits at only 400 V to ground. Fixed ×100 gain, ±4 V nominal input, 60 mA continuous per channel. As with the A400DI, the one condition is that the load must float: neither end may be grounded. If the device housing is earthed or the fixture ties one side down, this topology does not apply.
Overview
1600 Vpp is hard to get from one amplifier, and differential drive turns it into a matter of combining two ±400 V channels. The A800DI has the phase inverter built in: one channel outputs in phase, the other inverted, and the load sees the sum of the two. Beyond cost, this brings two engineering benefits. Voltage to ground stays at 400 V, so insulation, creepage and safety guarding are designed for 400 V rather than 800 V. And the phase relationship between the two outputs is fixed inside the instrument, not by cable lengths, so there is no timing skew, which at high swing and high frequency would appear directly as distortion at the load. The limit remains the floating-load requirement. In practice this topology is used for high-voltage electrostatic transducers, pushing large piezo stacks to their limits, and materials tests that need very strong fields. At 1600 Vpp the 60 mA continuous current per channel is still the binding constraint; size the unit from load capacitance and operating frequency to find the largest amplitude it can sustain. With the inverter unused it is a standard dual-channel ±400 V amplifier.
Key specifications
| Output voltage (per channel) | ±400V |
|---|---|
| Differential output (floating load across both channels) | Up to 1600Vpp |
| Fixed voltage gain | 100× |
| Output current (continuous) | 60mA |
| Input voltage range (nominal) | ±4V |
| Input impedance | 1 MΩ ∥ 30 pF |
| Output impedance | <0.1Ω (linear mode) |
| Bandwidth | DC to 1 MHz at 100 Vpp; DC to 300 kHz at the full 800 Vpp per-channel swing |
| Slew rate | 500 V/µs without load; about 160 V/µs rising and 100 V/µs falling into a 300 pF load |
| Channels | 2 (with phase inverter) |
| Max capacitive load | 300 pF maximum per the A800DI manual (the dual-channel datasheet lists 200 pF at full bandwidth) |
Features
1600 Vpp differential swing
Two ±400 V channels driving a floating load reach a potential difference that one amplifier cannot easily supply.
Still 400 V to ground
Insulation, creepage and safety guarding are designed for 400 V, not 800 V.
Phase fixed by the instrument
The built-in inverter removes the timing skew that cable-length differences would add, which matters most at high frequency and high swing.
The load must float
Neither terminal may be grounded; an earthed housing or a fixture that ties one side down rules this topology out.
Current is still the limit
60 mA per channel; load capacitance and operating frequency set the largest amplitude the unit can hold.
Falls back to a plain dual channel
With the inverter unused it is two independent ±400 V channels.
Typical applications
Piezo drive
Piezo actuator and ultrasonic transducer drive tests
Developers of piezo actuators, from nanopositioning stages to ultrasonic probes and fuel injector valves, need a ±4 V generator signal raised accurately to the drive level. The A800DI delivers up to ±400 V at ×100 gain through a low-distortion linear stage, so the displacement-versus-voltage curve of the element is measured without the driver adding error.
Differential drive
Counter-phase dual-channel drive for larger effective amplitude
When a device test needs more than a single ±400 V channel, the built-in low-voltage inverter feeds the CH1 signal inverted to CH2, so the two outputs run 180 degrees apart. A floating load such as an LC cell, an electrostatic MEMS actuator or an OLED electrode pair connected between the outputs sees ±800 V, or 1600 Vpp, which widens the high-voltage evaluation range considerably.
MEMS characterization
Pull-in voltage measurement of electrostatic MEMS actuators
Academic and industrial labs characterizing comb drives and cantilever resonators need a wideband, accurate high-voltage bias source. The A800DI accepts an arbitrary waveform generator output and drives the electrostatic actuator linearly across the sweep, so pull-in threshold, resonance drift and hysteresis are measured with a clean excitation.
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)
Model options (dual-channel models in the series)
Service options
Downloads
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