This innovation is a wideband, high-power, high-efficiency, all-solid-state microwave power module (SSMPM) or amplifier for a multifunction spacecraft payload that operates, depending on the need, as a radar system, communication system, or navigation system. The construction of the module is based on a wideband multi-stage amplifier design. The low-power stage is a high-efficiency GaAs pHEMT-based MMIC (monolithic microwave integrated circuit) distributed amplifier. The medium-power stage is either a high-efficiency GaAs pHEMT (high-electron-mobility transistor) or GaN HEMT-based MMIC distributed amplifier. The high-power stage is a high-efficiency GaN HEMT-based MMIC distributed amplifier.

Schematic of a fully Solid-State Microwave Power Module (SSMPM) with cascaded MMIC distributed amplifier stages having decade bandwidth.
The microwave power module does not include a traveling-wave tube amplifier (TWTA), and the high-power output stage is built around a GaN HEMTbased MMIC distributed amplifier instead of a TWTA. The distributed amplifier design is inherently capable of very wideband operation of typically a decade or more.

The microwave power module is small in size and lightweight. In addition, by substituting a transistor-based high-power amplifier in place of a TWTA in the output stage, the need for a kV-class electronic power conditioner (EPC) is eliminated, which further reduces the overall size and mass. GaN is a wide bandgap semiconductor, and devices constructed from this material can operate at elevated temperatures and are also inherently radiation-hard. GaN HEMTs typically operate at voltages as high as 30 V, which is closer to the spacecraft bus voltage, and hence the design of the DC-to-DC converter in the EPC is simplified.

HEMTs have much higher cut-off frequency ft and maximum frequency of oscillation fmax than MESFETs (metal-semiconductor-field-effect-transistors). Distributed amplifiers inherently have a very large-gain bandwidth product. The decade-wide bandwidth of the distributed amplifier employed here translates into pulse rise times on the order of a few tens of picoseconds, which is several orders of magnitude smaller than the nanosecond rise time required by the radar pulses.

This work was done by Rainee N. Simons and Edwin G. Wintucky of Glenn Research Center. NASA Glenn Research Center seeks to transfer mission technology to benefit U.S. industry. NASA invites inquiries on licensing or collaborating on this technology for commercial applications. For more information, please contact NASA Glenn Research Center’s Technology Transfer Office at This email address is being protected from spambots. You need JavaScript enabled to view it. or visit us on the web at https://technology.grc.nasa.gov/ . Refer to LEW-18717-1.