Differential amplifier
100 MHz LeCroy

The DA1855A is a stand-alone, high-performance 100 MHz differential amplifier. It is intended to act as a signal conditioning preamplifier for oscilloscopes, digitizers and spectrum analyzers, providing differential measurement capability to instruments having only a single-ended input. When used with a DA1855A, oscilloscopes can obtain Common Mode Rejection Ratio (CMRR) and overdrive recovery performance levels previously unobtainable.

Amplifier gain can be set to 1 or 10. A built-in input attenuator can be separately set to attenuate signals by a factor of 10, providing gains of 10, 1, or 0.1 and common mode dynamic range of ±15.5 V (÷1) or ±155 V (÷10). 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. Effective gain of the DA1855A, including probe attenuation, amplifier gain and attenuator settings, is automatically displayed.

The DA1855A has a bandwidth of 100 MHz, but any one of the three 3-pole bandwidth limit filters can be selected to reduce bandwidth to 20 MHz, 1 MHz or 100 kHz to limit noise above the frequency of interest.

The DA1855A output is carefully limited to ±500 mV, so that the oscilloscope is not overdriven by large inputs. This allows many oscilloscopes to directly measure the settling of D/A converters with 14-bit (60 ppm) precision, better than any other differential comparator.

The DA1855A features a built-in Precision Voltage Generator (PVG) that can be set to any voltage between ±15.5 volts (±10 volts in Differential Offset) with up to 100 µV resolution.