The DA1855A is a stand-alone, high-performance 100 MHz differential amplifier that acts as a signal-conditioning preamplifier for oscilloscopes, digitizers, and spectrum analyzers. It gives differential measurement capability to instruments that have only a single-ended input, and it provides the fastest overdrive recovery of any commercially available product of its type. When paired with the DA1855A, an oscilloscope can reach levels of Common Mode Rejection Ratio (CMRR) and overdrive recovery performance that it could not achieve on its own.

The amplifier's design targets measurements that would otherwise be limited by an oscilloscope's own overdrive recovery. With its ±500 mV limited output, it allows many oscilloscopes to directly measure the settling of D/A converters with 14-bit (60 ppm) precision. Using an attenuating probe, it enables in-circuit measurement of dynamic saturation in the switching devices of switch-mode power converters. In comparator mode it accurately measures relatively small signals riding on large AC or DC components, and in true differential offset mode it supports measurements such as changes to a transistor's base-to-emitter voltage caused by variations in temperature and/or current.

ValueTronics International stocks test and measurement equipment in our own 20,000 sq ft secure warehouse at 1675 Cambridge Drive in Elgin, Illinois. Every pre-owned unit is inspected and functionally verified in-house before it ships, while new units ship factory-sealed exactly as received from the manufacturer.

Brand Heritage

LeCroy Corporation, founded by Walter LeCroy in 1964, was acquired by Teledyne Technologies in 2012 and now operates under the Teledyne LeCroy brand.

Compare Other Models in This Series

The DA1855A is offered in several configurations built around the same high-performance 100 MHz differential amplifier core with its built-in Precision Voltage Generator. The configurations differ in channel count and in mechanical form factor, while sharing the same measurement architecture, bandwidth, CMRR, and comparator/differential-offset capabilities.

The single-channel DA1855A and the two-channel DA1855A-PR2 are each available in standard bench form or in a rackmount form (DA1855A-RM and DA1855A-PR2-RM), letting the same amplifier capability fit either a benchtop or a rack-integrated test setup.

Each pre-owned model below is its own dedicated product page with condition-matched pricing. Select the configuration that fits your channel-count and mounting requirements, and review that page for its specific pre-owned availability.

The base DA1855A is the single-channel (1 Ch) configuration with the integrated Precision Voltage Source, providing one channel of differential amplification with comparator and true differential offset modes.

The primary difference across the configurations is channel count: the DA1855A provides one channel, while the DA1855A-PR2 provides two channels of the same 100 MHz differential amplifier with Precision Voltage Source.

The second difference is mounting: the DA1855A-RM and DA1855A-PR2-RM add rackmount hardware to the single- and two-channel versions respectively. The DA1855A-PR2-RM must be ordered at time of purchase, with no retrofit available. See the comparison table for the configuration details.

Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.

Product Core & Specifications

Important: The DA1855A-PR2-RM rackmount configuration must be ordered at the time of purchase — it cannot be retrofitted.

Important: High-performance differential probes such as the DXC100 ÷10/÷100 high CMRR probes are recommended and are ordered separately. Optional probes increase the maximum input signal and common mode ranges in proportion to their attenuation ratio but do not exceed their maximum input voltage rating.

Important: The DXC-5100 high voltage probe pair requires the DA101 attenuator for full performance.

Important: DXC series probes must be used with DA Series Differential Amplifiers.

Recommended pairing: use the DXC100A ÷100/÷10 250 MHz high-CMRR passive differential probe pair, the high-performance probe recommended for the DA1855A.

About this Pre-Owned unit

This pre-owned unit is inspected and functionally verified in-house before it ships and is backed by our pre-owned warranty. To confirm its exact condition, firmware revision, installed options, or included accessories for your application before ordering, contact our Test Architects.

• Warranty included
• Functional verification included
• Standard Calibration Upgrade Options: No Calibration Required, NIST Traceable, Z540.1 or ISO 17025 with Data, Z540.3 Guardbanding with Data.
• Note that unnecessary accessories may not be included (contact Test Architect to confirm).

ValueTronics supplies both new and used test and measurement equipment. New units ship factory-sealed, exactly as received from the manufacturer; every used unit is inspected and functionally verified in-house at our 20,000 sq ft secure facility in Elgin, Illinois before it ships. Our Test Architects can help you select the condition, calibration, and configuration that fit your application.

Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.