Put some magic into amplifier design

The article presents guidelines for engineering evaluation of CAD systems and the use of Magic (Modern Analytical Generator of Improved Circuits) to illustrate the computer-assisted design of a two-stage broadband amplifier in stripline media. The five key criteria to evaluate a CAD system are cost, convenience, power, flexibility and support. The mechanics of operating Magic are discussed. Magic handles up to 500 circuit elements and up to 50 may be simultaneously optimized. The optimization process involves minimizing a weighted error function that is the difference between the desired response and the actual response over a specified band. Other Magic features include: computing circuit stability and other circuit responses; drawing Smith Charts or performing statistical, worst case or sensitivity analysis; considering additional frequencies; adjusting aims and weights; and reoptimizing to secure further improvements.