Frequency response

About: Frequency response is a research topic. Over the lifetime, 25705 publications have been published within this topic receiving 332249 citations.

An efficient small signal frequency analysis method of nonlinear circuits with two frequency excitations

Abstract: One of the excitations, 'carrier', is a large signal and an arbitrary T-periodic function of time. The other excitation, 'signal', is considered as a small perturbation to the periodic steady-state response driven by the carrier. To find a small signal frequency response for the 'signal', the method uses variational equations around the periodic steady-state response. These linearized time-varying differential equations are solved in the frequency domain using a time discretization method. The method can be used to compute the small signal frequency responses of nonideal switched capacitor filters, mixers, and other nonlinear circuits, if the circuit has a stable periodic response. The formulation of the problem, computational complexity of the method, error analysis, sensitivity analysis, implementation of the method, and some applications are covered. >

Small-signal dynamic modeling of HVDC systems

Abstract: This paper details the development of a linear continuous-time state model of the small-signal dynamics of a high-voltage direct current (HVDC) transmission system. The dynamics in the frequency range between 2 and 200 Hz on the DC side are of interest for the identification of possible stability problems and the design of the fastest level of converter controls. The state model is formed by representing the system as the collection of a number of interconnected subsystems. This approach is structured and flexible, and can be directly applied to other systems including FACTS. A small-signal state model of the CIGRE benchmark HVDC transmission system is formed, validated against PSCAD/EMTDC time-domain simulation, and used to determine the rectifier DC current control open-loop frequency response.

Meter and method for in situ measurement of the electromagnetic properties of various process materials using cutoff frequency characterization and analysis

Abstract: The method provides the following steps. Passing the process material through a frequency sensitive measurement cell. Exposing the process material to electromagnetic energy produced by a multi-frequency source. Controlling the multi-frequency source by a computer so as to vary the signal frequency such that an output signal is produced having a distinctive frequency response characteristic. Detecting the output signal and converting the signal to a digital representation. Analyzing the digital representation of the signal to determine the cutoff frequency. Determining the sharpness of the cutoff characteristic by mathematical algorithms. From the measured cutoff frequency and the sharpness of the cutoff characteristic, determining the dielectric constant and the conductivity of the material. Using stored calibration data or equations, computing and displaying the desired material property, e.g., the material's moisture content. And further, using the passband attenuation to determine the density of the material.

Design of low-power and low-voltage log-domain filters

Abstract: This paper describes a component-level mapping between linear- and log-domain filters. A modified multiple input class AB log-integrator with both f- and Q-tuning is presented. A 3/sup rd/-order elliptic filter derived from a LC ladder prototype is designed using the proposed log building blocks and including the log-domain implementation of the transmission zero. Simulated frequency responses, THD and SNR, obtained from large signal transient analysis, are given. The filter is designed for a 2 V supply and consumes 1.3 mW for a cutoff frequency of 10 MHz. It can easily be frequency tuned from 1 MHz to 30 MHz.