%0 Journal Article
%T Six-Port-Based Architecture for Phase Noise Measurement in the UWB Band
%A J. M. ¨˘vila-Ruiz
%A A. Moscoso-M¨˘rtir
%A E. Dur¨˘n-Valdeiglesias
%A L. Moreno-Pozas
%A J. de-Oliva-Rubio
%A I. Molina-Fern¨˘ndez
%J Journal of Electrical and Computer Engineering
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/646738
%X A six-port-based frequency discriminator for phase noise measurement is proposed. This circuit makes use of a delay line discriminator configuration, thus not requiring reference oscillator. Furthermore, the use of a six-port network allows an extremely simple and completely passive solution well suited for low power oscillator measurement. A detailed study of the architecture is performed including the system noise sources. Besides, a prototype of the proposed six-port based delay line frequency discriminator is evaluated. Phase noise measurements of a commercial RF VCO are performed and compared with the results obtained with commercial metrology equipment with good agreement. 1. Introduction The high data rate transmission requirements of current radiofrequency standards demand efficient and robust modulation techniques. One of these modulation techniques is Orthogonal Frequency Division Multiplexing (OFDM), which is widely used in wireless communications due to its good performance against noise and multipath effects. On the other hand, OFDM receivers are very sensitive to local oscillator phase noise, which produces adjacent channel crosstalk due to reciprocal mixing [1, 2]. This adjacent channel crosstalk increases bit error rate (BER) [3, 4]. Phase noise effects in radiofrequency communications are the reason why feedback systems, such as phase locked loops (PLL), have been used for phase noise reduction for 80 years [5, 6]. Moreover, a great amount of new on chip low noise oscillators designs are carried out every year [7, 8]. An outstanding issue, as important as the design of low phase noise oscillators, is the accurate measurement of their phase noise. Modern oscillators with low phase noise level require metrology systems with even more demanding specifications as well as measurement methods to compensate their limitations [2, 9]. Several methods have been defined for phase noise measurement, depending on the characteristics of the system to be measured. As a main distinction, these methods can be first classified depending on whether they require a reference oscillator or not. This differentiation is important, since reference oscillator phase noise will increase the noise floor of the measurement system. In order to increase the instrument sensitivity, ultralow phase noise reference oscillators are needed. Therefore, high performance systems that rely on reference oscillators are more expensive than other instrument systems. The group of phase noise measurement techniques that make use of a reference oscillator comprises the direct
%U http://www.hindawi.com/journals/jece/2014/646738/