The Application Of MoM In The Designing Of RF-Circuit

With the development of the modern communication technique, the frequency of communication systems are becoming higher and higher. In the MF to HF, and to RF band, even some frequencies in microwave band are used in some systems. With this movement, the demands for the designing of communication systems are getting stricter and the problems encountering in the designing are more difficult and complex to deal with. For example, in some systems, people require the devices have good abilities to withstand noise, and at the same time, have large power output at a high frequency. In 3G or B3G systems, how to design a mini antenna while it must have the same abilities as a mimo antenna is a hard problem. In RF-circuit designing, how to arrange the layout of the whole circuit so that it can reduce the interference in all possible aspects is also a hard one. As a RF engineer, to solve the above problems, a good CAD software is indispensable. The simulation software based on the moments method has some advantages such as accuracy, time reduction and wide usage, so it can be an important role in the designing of RF-circuit.Method of Moments(MoM), also called general Gallerkin method is an important numerical method for solving the differential and integral equations. It's very useful in solving the edge problems in electro-magnetic field. And in RF circuit designing, many problems can be sorted as the edge problems. This paper firstly introduces the basic theory and key techniques of MoM, then gives two examples to show the use of MoM in solving the problems in electro-magnetic field, after this, discusses the simulation software: Momentum and how it uses MoM to simulate circuits. Finally, the paper exhibits two practical designs of RF amplifiers(one is a power amplifier, and another is a low-noise amplifier) to show the simulator's advantages of MoM over the ordinary circuit simulator.