Modular construction of low-noise multi-stage f.e.t. amplifiers

A new amplifier modular structure has been developed to realize a 30 dB gain multi-stage f.e.t. amplifier for radar applications. Since the overall gain needed was very high, a multi-stage approach had to be adopted. Matched inputs and outputs of 50¿ were employed for each stage in order that individual stages could be characterized separately and adjusted if necessary. The cascading problem of these individual stages was resolved by the design of a rail modular technique. The amplifier has a gain greater than 30 dB over 1 GHz bandwidth at 9.3 GHz. The noise is less than 6 dB at temperatures up to 80°C. The modular construction described in this paper facilitates very rapid circuit design and assembly. It is readily adaptable to many different sub-assemblies using other devices (mixer diodes, negative resistance diodes, ferrite devices, etc.).