Highly Linear E-Band Traveling Wave Tube Amplifier

Linearizer Technology, Inc. (LTI) in association with L-3 Communications Corporation, Electron Devices Division (L-3 EDD) proposes to develop a linearized E-band TWTA. The goal of this program is to develop, fabricate, and test a compact linear E-band microwave power module (MPM) providing a minimum linear output power of 45 W with an efficiency of 30% from 81 to 86 GHz. Linear performance will be based on supporting Quadrature Amplitude Modulation (QAM). A goal will be an amplitude modulation/phase modulation (AM/PM) of less than 2 °/dB from small signal up to saturated power across the band. It is projected that to achieving 45 W of linear output power will require a TWT producing a saturated output power of about 90 W across the frequency band. The realization of this TWT will be leveraged on work presently underway at L-3 EDD, under internal funding, in W-band. LTI will development the E-band pre-distortion linearizer required to achieve the required linear performance. This work will make use of LTI’s experience in producing linearizers for the Ka and Q-band frequency ranges. BENEFIT: Efficient linear power amplifiers are needed for satellite communication (SATCOM) in the newly allocated E-band (81-86 GHz) to support the transmission of Airborne Intelligence Surveillance and Reconnaissance (AISR) data. These transmissions utilize complex digital modulation as Quadrature Amplitude Modulation (QAM) in which the peak to average power ratio is high, and result in a non-constant envelope. Power amplifiers made for these modulations must be highly linear in order to minimize distortion that can negatively affect adjacent channel signals and signal quality (bit error rate) [1,2]. To achieve the required level of linearity, it is common practice to operate amplifiers at reduced power, a high level of output power backoff (OPBO). The consequences of this approach are a very low efficiency, over-sized and heavy transmitters/amplifiers and power supplies, extra unnecessary heat generation, and higher costs. A millimeter-wave these factors can make a communication system impractical to implement, particularly for power-consumption-sensitive applications such as SATCOM.. At millimeter-wave the most efficient form of amplification is normally a TWT. However TWTs are not the most linear devices. For this project it proposed to develop a compact linear TWTA for E-band in the form of a linearized microwave power module (MPM). L-3 Communications Electron Devices Division (L-3 EDD) builds a variety of MPMs for military SATCOM and data link applications. The compact package and high efficiency of the MPM makes it an ideal amplifier for military mobile communication applications