Microwave Diode Packages -- Know What You Are Getting

By K. R. Philpot
Director of Applications, Microsemi-Lowell

There is no subject that causes more problems and confusion for users of microwave diodes than the effects of the diode package. Packages always limit the performance of the circuit design, sometimes in unexpected ways. This paper will discuss the different types of packages available, the attributes of each, and the effects one might expect when used in some common circuit applications.

Packages are a necessary evil. In a perfect world, all designs would make use of the unpackaged die, installed eutecticly and wire bonded into the circuit. But microwave diode packages afford protection for the die, ease of handling, and a means of efficient automated circuit assembly. Any discussion of microwave diode packages must start with an understanding of the detrimental attributes that packages bring.

Parasitics
Parasitics are unwanted electrical and mechanical attributes. They always serve to limit circuit performance. Package types have various combinations of different parasitics. The right choice of packages is always a compromise of some sort. Often it is the lesser of several evils.