20 GHz Radiation Hardened SSPA for SATCOM Downlinks

The next generation of solid-state power amplifiers (SSPAs) is required to meet the demands of high data rate battlefield communications at K-band. Military satellite communication systems must achieve higher signal capacity by employing complex modulation schemes in closely spaced channels. This SBIR effort will focus on innovative approaches towards realizing ultra-linear 20 GHz SSPAs with minimized adjacent channel interference. Improved linearity is the key to enabling additional adjacent channels and faster data transfer.

In a traditional design approach, each stage must be oversized to maintain linearity, resulting in a low-efficiency amplifier. Our design methodology is to force the non-linear characteristics of each stage to work together and minimize overall non-linearity. By allowing each stage to be non-linear, keeping the overall linearity to a minimum, the amplifier can operate at a reduced back-off condition at higher efficiency. The design goal is to accomplish the best trade-off between efficiency and linearity in multi-stage amplifiers. 

Optimization Priorities:

• Linearity
• Efficiency
• Output power

Balanced Solution:

Design and deliver 2 W GaAs or GaN SSPA with external linearizer circuit capable of suppressing spurious signals to below -40 dBc without sacrificing efficiency (at least 35%). A cost-benefit analysis will determine advantages for GaAs and GaN at this frequency.