1145A Agilent Active Probe

Surface-mount packages on PC boards have become the norm rather than the exception. In the future, nearly 100 percent of both sides of a typical PC board will use SMDs. As a result, bulky probes may become useless as package sizes get smaller and smaller.

The 2-channel Agilent 1145A provides easy and reliable connection to SMDs on PC boards and backplanes, while delivering active probe performance down to the tip. Its unique design also presents a powerful combination of industry-standard compatibility and superior reliability. The probe’s basic contact is a standard 25-mil square pin socket that houses only passive circuitry. The active circuitry is contained in a plastic pod 13 inches from the tip. This design ensures a small, lightweight, and rugged tip.

The electrical performance of the 1145A is unmatched by any off-the-shelf probe designed for SMD probing. The probe combines high bandwidth, high input resistance, and low input capacitance. This combination is superior to that of passive divider probes that have higher input capacitance because it provides minimal circuit loading at high and low frequencies (see the Impedance vs. Frequency graph). As signal speeds increase, passive divider probes don’t deliver the performance needed. This lower performance can result in waveshapes that do not represent the actual signal. The 1145A used with an 54542A scope, for example, introduces the equivalent of only ½ of a typical CMOS gate load (approximately 3.0 pF per gate) to a CMOS circuit. Other SMD probes used with comparable scopes can introduce 1½ or more gate loads to the circuit under test. 

A versatile set of accessories lets you probe most any SMD package. The standard socket also makes the 1145A compatible with probing adapters from other vendors for faultfree probing of SMDs including 5-mil JEDEC, 0.5-mm EIAJ, 0.65-mm EIAJ packages.