Level Range Extension Of The R&S®SMW200A Using An External Amplifier

Rohde & Schwarz provides a comprehensive guide for extending the output power of the R&S®SMW200A vector signal generator using an external amplifier. This is particularly useful for testing RF devices that require higher input power than the generator can provide, or when long cable connections introduce significant signal loss. The document outlines methods for safely configuring the test setup, including limiting output power to prevent damage to devices and shifting the power reference plane to the device under test (DUT) using an R&S®NRP power sensor.

Two main strategies are presented: using a simple level offset for stable-gain setups, or employing active power control with NRP Power Control for variable-gain channels. For more complex setups where signal integrity is critical, the note discusses how to mitigate linear and nonlinear distortions introduced by the external amplifier using the R&S®FSW signal and spectrum analyzer. This includes generating and applying a Hammerstein model via Direct Digital Pre-Distortion (DPD) to achieve accurate signal compensation.

The note also covers a more advanced use case where both the amplifier and DUT are pre-distorted together to find optimal DUT performance using Direct DPD. Practical setup instructions, parameter guidelines, and safety precautions are included throughout, making this document a valuable resource for engineers seeking to optimize high-frequency RF test environments with extended power requirements. Tools used include the R&S®SMW200A, R&S®NRP, and R&S®FSW, and the note emphasizes flexibility depending on test objectives and hardware configurations.