Multiplier circuits keep phase clean

It is pointed out that signal requirements at microwave frequencies have become more stringent as radar and communication systems have grown in complexity and improved in performance. These improvements have increased the need for generating and measuring low-noise signals. A review of phase-noise concepts is conducted, and an analysis of generation and measurement techniques is performed. Since frequency and phase are related, either phase fluctuations or frequency fluctuations can describe the same signal. The causes of phase noise are examined. Phase noise can be a major limiting factor in frequency conversion applications dealing with signals that span a wide dynamic range. Attention is given to the requirements for an ideal low-noise source, the production of clean microwave signals, the two basic principles of operation for multipliers, the two-source technique, and a system for automatic measurements.