Optimal noise matching of 0.25 micron gate GaAs MESFETs for low power personal communications receiver circuit designs

On the performance of low-noise low-DC-power-consumption cryogenic amplifiers

“…DC and S-parameter of many GaAs and InP transistors were measured on wafer both at room temperature and cryogenic temperature. From these measurements we could extract the noise models [6][7][8][9][10][11][12][13][14] which were later used at cryogenic temperatures for the amplifier design. At low temperature the transconductance of both InP and GaAs transistors increase, Figs.…”

“…Thus, in order to improve the accuracy of the noise measurements and validate the noise models both at room and cryogenic temperatures a special pre-matched circuit was designed. This pre-matched circuit includes the input matching network calculated from the extracted model, transistor bonded in the fixture and the necessary bias networks in order to stabilize the transistor at cryogenic Another issue is selecting the right device size so to obtain optimum input capacitance Cgs, high ft and low Rn and thus to make the matching networks rather simple in order to achieve broadband operation [12,13], because the noise performance depends linearly on ft(gm) and (Td and Tg)^0.5. These relations are general for all FETs.…”

“…In recent years the performance of microwave GaAs and InP transistors improved significantly and many successful designs with extremely good parameters have been reported [1][2][3][4][5]. This, together with the existence of simple and accurate models [6][7][8][9][10][11][12][13] improved the quality of the microwave cryogenic amplifiers and excellent results were achieved in recent years. For many different applications, such as deep space ones a very low DC power dissipation is one of the most important requirements in the system.…”