30 GHZ REFLECTION MODE FET SOLID STATE POWER AMPLIFIER

A PHASE 1 PROGRAM IS PROPOSED TO PERFORM A DESIGN STUDY TO DEMONSTRATE THE FEASIBILITY OF REALIZING A LOW COST KA-BAND (30 GHZ) REFLECTION MODE FET SOLID STATE POWER AMPLIFIER (SSPA), EXHIBITING A MINIMUM 16W RF OUTPUT POWER OVER AT LEAST 1GHZ OPERATING BANDWIDTH, FOR 30/20GHZ SATCOM UPLINK TRANSMITTER USAGE. THE PROPOSED SSPA WILL EXHIBIT, AT KA-BAND THE HIGH DEGREE OF LINEARITY NECESSARY FOR HIGH CAPACITY TDMA OR SCPC MULTI-LEVEL PCM FORMAT TRANSMISSION ACHIEVABLE AT LOWER FREQUENCIES FROM CONVENTIONAL FET POWER AMPLIFIERS BUT WITH HIGHER EFFICIENCY, GREATER BANDWIDTH, LOWER PASSBAND GAIN/DELAY RIPPLE AND FEWER DEVICES. MOREOVER, IT WILL ENABLE THE USE OF LOWER FREQUENCY FET'S (KU-BAND), WHICH NORMALLY CANNOT OPERATE IN CONVENTIONAL TOPOLOGIES AT KA-BAND. THE REFLECTION MODE FET SSPA WILL CONSIST OF A CORPORATE CASCADE OF CIRCULATOR-COUPLED FET AMPLIFIER STAGES, EACH OPERATED IN THE ONE-PORT NEGATIVE RESISTANCE REFLECTION AMPLIFICATION MODE. IN EACH CIRCULATOR-COUPLED STAGE, AN UNPACKAGED KU-BAND FET IS PROPERLY EMBEDDED IN A ONE PORT KA-BAND MOUNT WITH SUFFICIENT POSITIVE GATE/DRAIN REACTIVE FEEDBACK TO GENERATE THE REQUIRED RESONANT NEGATIVE IMPEDANCE. USE OF THE REFLECTION MODE FET IN LIEU OF AN IMPATT AMPLIFIER IN THE 30 GHZ UPLINK TRANSMITTER PROVIDES THE PERFORMANCE ADVANTAGES OF GREATER INPUT/OUTPUT LINEARITY FOR MULTILEVEL PCM SIGNALS, AND LOWER POTENTIAL LARGE QUANTITY COSTS DUE TO THE ABUNDANCE OF LOW COST KU-BAND FET'S AS COMPARED WITH KA-BAND IMPATT'S.