Lecroy DA1855 High-performance Differential Amplifier, 100MHz

The LeCroy DA1855 is a differential amplifier delivering DC to 100 MHz bandwidth for precision signal conditioning across oscilloscopes, digitizers, and spectrum analyzers. Selectable gains of 1× and 10× combined with a 10× input attenuator provide effective gains of 10, 1, or 0.1 - with automatic display of combined effective gain accounting for probe, amplifier, and attenuator settings. An exceptional 100,000:1 (94 dB) CMRR and overdrive recovery enable accurate differential measurements in high-noise environments.

Technical Specifications

• Bandwidth: DC to 100 MHz


• Selectable gain: 1× and 10×


• Input attenuator: 10× selectable attenuation


• Effective gain display: Automatic combined gain calculation


• Bandwidth limit filters: 100 kHz, 1 MHz, 10 MHz, 20 MHz, or full 100 MHz Precision Voltage Generator (PVG)


• Output range: ±15.5 V (comparator mode); ±10 V (differential offset mode)


• Resolution: 100 µV / 5-1/2 digit


• DC accuracy: 0.05% + 500 µV (15°C to 45°C)


• PVG voltage accuracy: ±1% of reading ± 500 µV


• Temperature coefficient: <5 ppm/°C of full scale Performance Characteristics


• CMRR: 100,000:1 (94 dB) at DC; ≥50,000:1 (94 dB) at 70 Hz and 100 kHz; ≥316:1 (50 dB) at 10 MHz


• Overdrive recovery: From 400 V input signal to <100 mV (÷100 probe) in 100 ns; to <1 mV (10× gain) in 100 ns


• Input noise (10× gain): <4 nV/√Hz broadband


• DC drift (10× gain): 50 µV/°C


• Rise time: <3.5 ns typical Auto-Zero & Control


• Auto-zero: Adjusts DC balance on each gain change; sets output to zero when 0.0 V selected


• Control interface: Full control via ProBus from compatible Teledyne LeCroy oscilloscopes

Key Features

• Selectable bandwidth limiting via three 3-pole low-pass filters


• Front-panel PVG control with rear-panel output connector for external use


• Differential offset accuracy (referred to input) down to 0.1% + 50 µV + PVG error at 10× gain with ÷1 attenuator

Typical Applications High-speed data acquisition, communications signal integrity testing, and precision differential measurements where common-mode rejection and rapid overdrive recovery are critical.

Compatibility & Integration Direct instrument control via ProBus interface from Teledyne LeCroy oscilloscopes. External PVG output available for standalone differential comparator or offset voltage applications.