Microwave Electronics Products


Microwave SSPA Selection Guide

The Microwave & RF Solid State Power Amplifier (SSPA) product line was designed for use in the most demanding applications, including Airborne, Missile, Radars and Communications. They are also a practical solution for more benign laboratory or field Test Systems. These diverse applications are made possible by the use of today’s cutting edge technologies for design and manufacturing of the SSPAs. As a result, these RF SSPAs provide high performance, reliability and cost effective alternatives to applications currently using Traveling Wave Tube (TWT) Amplifiers. All microwave SSPAs are designed using the Power Summation concept (Fig1) which provides a graceful degradation capability not found in TWTs and critical to mission completion.








The product line supports both X and Ku Band applications with band width up to 10% and offers peak power outputs up to 400 Watts. Successful solid state power amplifier designs have utilized Gallium Arsenide or Gallium Nitride power devices depending upon which was better suited for the application. The flexibility of the microwave SSPA design provides the ability to extend to adjacent frequency bands requiring only a short development time at very low risk.

Power Summation for Solid State Power Amplifier
Fig. 1: Power Summation



  • X and Ku Bands
  • Band Width 5%
  • High Power - up to 400W
  • High Reliability
  • Airborne Applications
Custom Solid State Power Amplifier (Microwave SSPA)
Custom SSPAs
Kratos Solid State Power Amplifier (Microwave SSPA) 

The RF input to the solid state power amplifier (see fig. 2), is pre-amplified and split into several parallel symmetric branches. Each branch includes a power amplifier section (PA). This distributed design of the microwave SSPA results in built in redundancy and graceful degradation of output power should any individual PA section fail. Each branch includes a current sense alarm indication which is monitored and fed to the RF SSPA controller. The amplified outputs of all the symmetric branches are summed up in a passive combing network which routes the resultant high power to the output of the RF SSPA.

A compact and highly efficient switching Power Supply Unit (PSU) is built into the solid state power amplifier. This state-of-the-art PSU design ensures that any contribution of phase noise and spurious signals are significantly reduced at the RF output. The microwave SSPA control section includes a Modulator which switches the DC lines of the individual PA sections On/Off to achieve the required Pulse Width, Pulse Repetition Interval and Duty Cycle. The SSPA Monitoring section includes Built-in-Test capability which receives indications from critical internal subassemblies, including the PA sections, thereby constantly monitoring the condition of the microwave SSPA.

Most of our solid state power amplifier designs are custom, deriving from Customer specifications because of the differing requirements for specific applications such as Airborne Radars and Missile Seekers. There are, however, many applications which can be served by more generic solid state power amplifiers as summarized in the below table. They are offered as Special Catalog SSPAs and intended to provide the user with a proven, cost effective solution rather than a new design.


Microwave SSPA 400W Block Diagram

Fig 2: SSPA 400W Block