Genetic-algorithm-based synthesis of differential amplifiers with complex-impedance terminations

A genetic-algorithm-based technique for the automated synthesis of schematics of microwave differential amplifiers loaded on complex-impedance terminations is presented. As an example, a 1.5-5 GHz 0.25 μm SiGe BiCMOS MMIC buffer amplifier used as a local oscillator (LO) driver for double-balanced mixer is automatically designed. This pseudo-differential LO amplifier provides power gain G
_T
= 15 dB±0.5 dB and 1-dB compression point P
_1db
more than 18 dBm. Chip size is 1.2×2.1 mm
²
.