Detection of EMI sources in portable radios

The digital signalling of certain communication products (e.g., trunked radios) requires that high speed logic and RF circuits be associated. Very often the close proximity of logic devices to RF boards can cause undesired desense phenomena, which, if not identified early in the design phase, add costs and delays to the delivery of a new product. This paper describes a simple device that can help the designer identify potential EM interference sources and characterize their strength and nature. Some EM signatures, over a broad band and at a single frequency, of a high speed logic board are shown.