Multiband Passive Intermodulation Testing

Accurate and rapid PIM characterization of communications components

Passive intermodulation (PIM) is a critical performance parameter that limits quality of service and capacity of current and new mobile communication systems such as cellular, PCS/4G/LTE and next generation 5G architectures. Passive intermodulation arises at high power levels due to the signal degradation effects of passive elements such as antennas, cables and filters within the transmission system. PIM cannot be removed by filtering alone. The reduction and control of PIM requires an understand­ing of sources, good design practice and associated manufacturing techniques. The ability to perform accurate and repeatable PIM measurements is key to the success­ful realization of advanced communication systems.

A new PIM test solution from Power Technology Systems (PTS) and Keysight address­es the need of component suppliers, integrators and service providers to measure passive intermodulation effects. The solution uses the Keysight E5072A ENA series network analyzer and the N5171B EXG signal generator to provide multiband PIM testing capabilities. The system integrates intermodulation distortion measurements with S-parameter characterization to fully qualify mobile communications compo­nents and sub-systems.

Passive intermodulation testing uses two independent high power (20 W typical) sig­nals in the cellular transmit band of interest. These create intermodulation distortion products in the receive band, which can be measured to characterize the amount of PIM present. The signals to be measured are small and require a noise floor in the test instrument of 10 dB better than the device-under-test. This will typi­cally require sensitivity of better than -173 dBc, which is achieved by using the advanced measurement capabilities of the Keysight ENA.

Multiband Passive Intermodulation Testing

PIM testing guidelines are defined in the IEC-62037 standards. These guidelines include both fixed and swept frequency measurements. The new system is compat­ible with IEC guidelines and provides both high measurement accuracy and rapid test speeds.

Higher test speeds are achieved through the built-in frequency offset functions in the Keysight network analyzer and signal generator. The frequency offset functions are set by internal firmware eliminating the need for additional external instruments. This reduces significantly the time required to reconfigure the test system for different frequency bands and allows easy configu­ration of the system to implement the IEC-62037 tests. The system can be configured for use in design, production or quality assurance.

With the new mul­tiband PIM testing system from PTS and Keysight you can achieve accurate and fast PIM characteri­zation of your passive components and sub-systems.