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    Phase-noise measurement using two inter-injection-locked microwave oscillators

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 54, Issue 7 , 2006 , Pages 2993-3000 ; 00189480 (ISSN) Nick, M ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2006
    Abstract
    Phase noise in two mutually coupled oscillators is analyzed by the describing function method, and the after-lock phase noise of the oscillators is calculated in terms of their free-running phase noise. A new phase-noise measurement technique based on inter-injection locking of two similar oscillators is proposed. Experimental results are presented, which confirm the theory. It is shown that in the case of zero phase of coupling coefficient, the system is in the optimum state where the only required parameter for the measurement is the locking bandwidth. In this optimum state, as far as the locking bandwidth is measured correctly, imperfections such as the frequency drift, parameters... 

    An analytical approach in analysis of local oscillator near-the-carrier AM noise suppression in microwave balanced mixers

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 57, Issue 1 , 2009 , Pages 760-766 ; 00189480 (ISSN) Kheirdoost, A ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2009
    Abstract
    In this paper, a new formulation based on conversion matrix method is proposed to analyze "near-the-carrier local ocillator (LO) noise" down conversion to IF in microwave mixers. This method could be easily applied to analyze LO noise down conversion in any type of mixer. Practical results of this method have been compared with the envelope method and measurement results. It is shown that despite the conventional AM noise suppression in balanced mixers, the near-the-carrier LO noise suppression does not occur necessarily at the center frequency of hybrid in balanced mixers. AM noise suppression values are predicted precisely. © 2009 IEEE  

    Continuum modelling of a circular planar array of coupled microwave oscillators

    , Article European Microwave Week 2009, EuMW 2009: Science, Progress and Quality at Radiofrequencies, Conference Proceedings - 39th European Microwave Conference, EuMC 2009, 28 September 2009 through 2 October 2009, Rome ; 2009 , Pages 1349-1352 ; 9782874870118 (ISBN) Tooni, S ; Banai, A ; Sharif University of Technology
    Abstract
    in this paper the phase distribution in an array of coupled oscillators arranged on a circular surface is discussed. Coupling is considered to be weak and each oscillator is coupled to its four nearest neighbours. In a continuum limit where the number of oscillators goes to infinity a theoretical formulation in polar coordinates is proposed to describe the dynamic behaviour of phases of the array elements. A Green's function for phase distribution of the array is proposed in terms of its normalized eigenfunctions. Beam steering can be done via detuning the edge oscillators. © 2009 EuMA  

    An analytical approach in analysis of local oscillator near-the-carrier AM noise suppression in microwave balanced mixers

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 57, Issue 4 , 2009 , Pages 760-766 ; 00189480 (ISSN) Kheirdoost, A ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2009
    Abstract
    In this paper, a new formulation based on conversion matrix method is proposed to analyze near-the-carrier local ocillator (LO) noise down conversion to IF in microwave mixers. This method could be easily applied to analyze LO noise down conversion in any type of mixer. Practical results of this method have been compared with the envelope method and measurement results. It is shown that despite the conventional AM noise suppression in balanced mixers, the near-the-carrier LO noise suppression does not occur necessarily at the center frequency of hybrid in balanced mixers. AM noise suppression values are predicted precisely. © 2006 IEEE  

    Statistical definition of locking bandwidth in an array of synchronised microwave oscillators

    , Article IET Microwaves, Antennas and Propagation ; Volume 2, Issue 1 , 2008 , Pages 74-81 ; 17518725 (ISSN) Hajian, H ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2008
    Abstract
    Arrays of N weakly coupled oscillators are considered in different configurations. The locking bandwidth for these arrays is defined statistically. Various factors affecting the locking bandwidth and the effect of the coupling network topology on locking bandwidth are studied by solving the dynamic equations of the array numerically. The analytical locking bandwidth for two configurations of arrays is computed and the results are compared with the numerical solution of dynamic equations. © The Institution of Engineering and Technology 2008  

    Phase Noise Reduction of Microwave Oscillator Using Interferometric Technique

    , M.Sc. Thesis Sharif University of Technology Salarpour, Mehdi (Author) ; Banayi, Ali (Supervisor)
    Abstract
    In today’s microwave communication, oscillators play a very important role as signal sources, so, the design of an oscillator with suitable parameters can affect the final performance of a communication system. Among different parameters, phase noise is of utmost importance since this parameter can lead to interference in multi-frequency channel systems and thus its estimation and measurement is vital. In an oscillator, in addition to measurement, the most important problem is to reduce phase noise. In fact, for improving the performance of a transmitter-receiver ( e.g. receiver sensitivity ), one of the solutions is using a local oscillator with low phase noise. Our purpose in this project... 

    Analytical prediction of the main oscillation power and spurious levels in optoelectronic oscillators

    , Article Journal of Lightwave Technology ; Vol. 32, issue. 5 , 2014 , pp. 978-985 ; ISSN: 07338724 Hosseini, S. E ; Banai, A ; Sharif University of Technology
    Abstract
    We use a nonlinear analytic approach to predict the main oscillation mode power and spurious levels in ultrapure microwave optoelectronic oscillators (OEOs). This approach takes into account N simultaneously mode falling inside the RF filter bandwidth and calculates all the dominant InterModulation Products (IMPs) that fall in the fundamental zone. We show that nonlinear microwave photonic links exhibit the capture effect. By considering this effect, we derive analytical expressions that govern the behavior of the OEOs in the steady state. We find that when the small-signal open-loop gain is increased beyond a critical value, OEOs start a multimode operation from which the spurious levels... 

    Vibration sensitivity reduction of two microwave oscillators using inter-injection locking technique

    , Article IET Microwaves, Antennas and Propagation ; Volume 7, Issue 13 , October , 2013 , Pages 1102-1112 ; 17518725 (ISSN) Modarresi, M. R ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2013
    Abstract
    Phase noise is one of the most important specifications of microwave oscillators. External factors such as mechanical vibrations increase the phase noise of the oscillator. A novel technique is introduced to reduce vibration-induced phase noise using inter-injection locking of two coupled oscillators. Two similar oscillators with equal free running frequencies are chosen and are subjected to sinusoidal vibration. The mechanical configuration is such that vibration sensitivity vector increases the frequency of one oscillator and decreases the other one's frequency of oscillation. Coupling these two oscillators using inter-injection locking, the common after-lock frequencies of both... 

    Sensitivity improvement of Phase-Noise Measurement of mcrowave oscillators using if delay line based discriminator

    , Article IEEE Microwave and Wireless Components Letters ; Volume 26, Issue 7 , 2016 , Pages 546-548 ; 15311309 (ISSN) Salehi Barzegar, A ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    Abstract
    The conventional delay-line discriminator method for phase noise measurement is modified to achieve better sensitivity. In the proposed technique, to decrease delay-line loss, the under-test oscillator's microwave frequency is down-converted by another oscillator, and delay-line is implemented in the IF range. Full validation of the technique is presented. In adition, we experimentally demonstrate that system sensitivity is considerably improved compared to the conventional method  

    A New Method For Phase Noise Measurement of Microwave Oscillators Using Phase Shifter-Less Frequency Discriminator

    , Ph.D. Dissertation Sharif University of Technology Gheidi, Hamed (Author) ; Banai, Ali (Supervisor)
    Abstract
    In this thesis, a modified method based on frequency discriminator technique is presented for measuring phase noise of microwave oscillators. In the proposed method, the phase shifter is omitted. In contrast, a 90° hybrid with one more channel containing a phase detector, and an LNA is added to the measurement setup. It can be said that an I/Q phase noise detection has been developed. With the proposed method, tuning of the variable phase shifter is not needed anymore. Therefore, the measurement is done automatically and as a result the measurement time is decreased. Beside the wideband property of the new technique, another considerable advantage is that the method is theoretically self... 

    New Mathematical Methods for Oscillation and Nnoise Spectrum Analysis in Microwave Oscillators in the Time and Frequency Domains

    , Ph.D. Dissertation Sharif University of Technology Jahanbakht, Sajad (Author) ;
    Abstract
    New mathematical approaches for noise and oscillation analysis of oscillators are presented. First a new approach for computing the phase noise spectrum of microwave oscillators at every offset frequency from the carrier is introduced. This method uses the harmonic balance formulation to obtain time domain functions used in the existing time domain phase noise analysis methods to compute the phase noise spectrum. In spite of the large signal nature of the phase noise in oscillators, it is analytically proved that for the purpose of phase noise calculations for moderate offset frequencies, the phase noise process can be considered as a small signal stationary process. By this consideration, a... 

    Phase-shifterless phase-noise measurement of microwave oscillators using high-Q cavity frequency discriminator

    , Article 81st ARFTG Microwave Measurement Conference: Metrology for High Speed Circuits and Systems ; 2013 ; 9781467349826 (ISBN) Gheidi, H ; Banai, A ; Sharif University of Technology
    2013
    Abstract
    This paper presents application of high-Q cavity resonator in phase-shifter less technique. A mathematical analysis is presented to show the dependency of the measured phase noise in terms of loaded quality factor and resonance frequency of the high-Q cavity resonator. Experimental measurements resulted from different methods for a synthesized oscillator at 9.976 GHz show great validity and accuracy of the proposed technique. This technique needs no tuning for the phase-shifter and can introduce better sensitivity compared to the setup that uses a delay-line as a frequency discriminator element due to much lower insertion loss particularly at high carrier frequencies. The sensitivity of -113... 

    Evaluation of beam steering in circular planar array of coupled microwave oscillators

    , Article International Journal of RF and Microwave Computer-Aided Engineering ; Volume 21, Issue 4 , 2011 , Pages 383-391 ; 10964290 (ISSN) Tooni, S ; Banai, A ; Farzaneh, F ; Sharif University of Technology
    2011
    Abstract
    A Green's function to describe the time behavior of the locking phases in a circular planar array of mutually coupled microwave oscillators is proposed. Using this Green's function the dynamic behavior of the array can be described for any arbitrary free running frequency of elements of the oscillator array. Beam steering is realized via detuning the edge oscillators of the array from a reference frequency and the beam direction is controlled by the amount of detuning for each oscillator at the edge. Some detuning functions such as sinusoidal, triangular and rectangular ones have been applied and, the resulting array patterns are compared with one another  

    Chaos control in virtual cathode oscillator by cathode structural optimization

    , Article Progress in Electromagnetics Research Symposium ; Volume 2015-January , 2015 , Pages 2225-2229 ; 15599450 (ISSN) ; 9781934142301 (ISBN) Hashemi, S. A ; Pirmoradi, A ; Zabeh, E ; Sharif University of Technology
    Electromagnetics Academy  2015
    Abstract
    In this paper, Virtual Cathode Oscillator as a microwave generator is studied concentrating on the nonlinear behavior of the microwave-plasma interaction that introduces chaos to the output voltage and power of the generator. It is shown that periodic oscillations of the electron beam strictly depend on the two most critical characteristics of the VCO, the input maximum voltage and the cathode radius. The chaos caused by the critical values of these two parameters, could restrict the maximum possible values of the input parameters, reducing the overall maximum output values. The effects of these two parameters are studied trough PIC-code simulations. The simulation results were used to... 

    Computation of the phase and amplitude noise in microwave oscillators and a simplified calculation method for far enough from the carrier offsets

    , Article IET Microwaves, Antennas and Propagation ; Volume 4, Issue 12 , 2010 , Pages 2031-2041 ; 17518725 (ISSN) Jahanbakht, S ; Farzaneh, F ; Sharif University of Technology
    2010
    Abstract
    New results regarding phase and amplitude noise analysis in microwave oscillators for moderate offset frequencies from the carrier are presented. Although the phase noise process in an oscillator is a large signal non-stationary process, it is proved that for the purpose of phase noise calculations for moderate offset frequencies, the phase noise process can be considered as a small signal stationary process and by this assumption, a valid approximation of the phase noise spectrum at these offset frequencies is obtained. By this consideration, a simplified approach for the purpose of the phase and amplitude noise spectrum calculations, at far enough from the carrier offset frequencies, by... 

    Phase-noise measurement of microwave oscillators using phase-shifterless delay-line discriminator

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 58, Issue 2 , January , 2010 , Pages 468-477 ; 00189480 (ISSN) Gheidi, H ; Banai, A ; Sharif University of Technology
    2010
    Abstract
    In this paper, a modified method based on the frequency discriminator technique for measuring phase noise of microwave oscillators is presented. In the proposed method, the phase shifter is omitted. In contrast, a 90° hybrid with one more channel containing a phase detector, and a low-noise amplifier is added to the measurement setup. It can be said that an in-phase/quadrature phase-noise detection has been developed. With the proposed method, tuning of the variable phase shifter is not needed anymore. Therefore, the measurement is done automatically, and as a result, the measurement time is decreased. Another considerable advantage of this method is that the method is theoretically... 

    Tunable low-Jitter low-drift spurious-free transposed-frequency optoelectronic oscillator

    , Article IEEE Transactions on Microwave Theory and Techniques ; Volume 65, Issue 7 , 2017 , Pages 2625-2635 ; 00189480 (ISSN) Hosseini, S. E ; Banai, A ; Kartner, F. X ; Sharif University of Technology
    Abstract
    We propose and theoretically and experimentally demonstrate a novel tunable spurious-free single-loop optoelectronic oscillator (OEO) with low drift and low-phase noise. In the proposed transposed-frequency OEO (TF-OEO), a nonreciprocal bias unit and an optical phase modulator in a fiber Sagnac interferometer function jointly as an intrinsically drift-free intensity modulator, which improves the long-term drift. Besides, a transposed-frequency low-noise filtered amplifier is used which replaces the conventional radio frequency (RF) bandpass filter (BPF) and RF amplifier with an intermediate frequency (IF) BPF, an ultralow phase noise IF amplifier, and a tunable local oscillator, to attain... 

    A new phase shifter-less delay line method for phase noise measurement of microwave oscillators

    , Article 38th European Microwave Conference, EuMC 2008, Amsterdam, 27 October 2008 through 31 October 2008 ; January , 2008 , Pages 325-328 ; 9782874870064 (ISBN) Gheidi, H ; Banai, A ; European Microwave Association, EuMA; MTT-S; GAAS ; Sharif University of Technology
    2008
    Abstract
    In this paper a new method for measuring phase noise of microwave oscillators based on delay line frequency discriminator is proposed. Elimination of phase shifter is the major advantage of this technique over the traditional delay line technique. By using this new technique, manual or electronic tuning of phase shifter to reach phase quadrature at the phase detector input ports is not needed anymore. A 90-degree hybrid is used in this technique and another path including a phase detector and LNA is added. Finally by using a dual channel FFT analyzer and performing some processing over the sampled data of the two channels, the phase noise of the oscillator will be extracted. A setup based on...