Sharif Digital Repository

Various researchers have contributed to the identification of the mass and stiffness matrices of two dimensional (2-D) shear building structural models for a given set of vibratory frequencies. The suggested methods are based on the specific characteristics of the Jacobi matrices, i.e., symmetric, tri-diagonal and semi-positive definite matrices. However, in case of three dimensional (3-D) structural models, those methods are no longer applicable, since their stiffness matrices are not tri-diagonal. In this paper the inverse problem for a special class of vibratory structural systems, i.e., 3-D shear building models, is investigated. A practical algorithm is proposed for solving the inverse... 

This paper presents a new architecture for a DLL based frequency synthesizer for wireless transceivers. Owing to its DLL based nature, the synthesizer generates the target frequencies with minimum phase noise and jitter. To cover the desired frequency proposed architecture consists of mixer and divider. As an example, VHF frequency band of IRAN is covered. The circuit level design guidelines and power consumption trade-offs are presented. It was shown that for the mentioned standard a 40 delay cell and 9 switches for switching channels is sufficient. Simulation results confirm the analytical predictions  

This paper presents a new architecture for a DLL based frequency synthesizer for wireless transceivers. Owing to its DLL based nature, the synthesizer generates the target frequencies with minimum phase noise. The proposed architecture takes the advantage of a combination of a frequency divider and an edge combiner to create the desired frequencies. As an example, the synthesizer is adopted to create the channel frequencies of French DVB-H/T standard. The circuit level design guidelines and power consumption trade-offs are presented. It was shown that for the mentioned standard a mere 6 stage delay line is sufficient. Simulation results confirm the analytical predictions  

A multi-band frequency synthesizer for In-phase and Quadrature (I/Q) LO signal generation in Digital TV tuners is presented. Using divisor numbers other than powers of 2 (2 n ) for quadrature generation, reduces the required frequency range of the VCO, hence the number of VCO circuits, in multi-band frequency synthesizers. In the proposed synthesizer, VHF, UHF and L-band frequencies are covered with only one VCO. This is achieved by using a novel divide-by-3 circuit which produces precise I/Q LO signals. The VCO tuning range in this design is 2,400-3,632 MHz which is covered by a 6-bit switched-capacitor bank. A fast adaptive frequency calibration block selects the closest VCO frequency to...