Case Study in Active Circuit Design (FET Amplifier)

The different steps of the CAD design process of a microwave active circuit are described. It is not the intention to repeat the instruction manual of a commercially available CAD software package. The CAD approach presented, does not require the use of a synthesis program for cost considerations. The active device selection, the approximate design method (necessary in case no synthesis program is available), the computer aided optimisation, the manufacturing and the testing of the hardware are discussed for both examples. Two microwave FET amplifiers with different specification requirement are discussed. The design of ann Intermediate Power Amplifier (IPA) in the 5.8 to 6.5 GHz is presented. In view of the application in SCPC (Single Channel Per Carrier) Satellite Ground Station, a stringent linearity requirement is imposed. A flatness of 0.25 dB over any 36 MHz transponder bandwidth is also required.