124 research outputs found
A new nonlinear time-domain op-amp macromodel using threshold functions and digitally controlled network elements
A general-purpose nonlinear macromodel for the time-domain simulation of integrated circuit operational amplifiers (op amps), either bipolar or MOS, is presented. Three main differences exist between the macromodel and those previously reported in the literature for the time domain. First, all the op-amp nonlinearities are simulated using threshold elements and digital components, thus making them well suited for a mixed electrical/logical simulator. Secondly, the macromodel exhibits a superior performance in those cases where the op amp is driven by a large signal. Finally, the macromodel is advantageous in terms of CPU time. Several examples are included illustrating all of these advantages. The main application of this macromodel is for the accurate simulation of the analog part of a combined analog/digital integrated circui
Passive Switched Capacitor RF Front Ends for Spectrum Sensing in Cognitive Radios
This paper explores passive switched capacitor
based RF receiver front ends for spectrum sensing. Wideband
spectrum sensors remain the most challenging block in the software
defined radio hardware design. The use of passive switched
capacitors provides a very low power signal conditioning front end
that enables parallel digitization and software control and
cognitive capabilities in the digital domain. In this paper, existing
architectures are reviewed followed by a discussion of high speed
passive switched capacitor designs. A passive analog FFT front end
design is presented as an example analog conditioning circuit.
Design methodology, modeling, and optimization techniques are
outlined. Measurements are presented demonstrating a 5âGHz
broadband front end that consumes only 4âmW power
Differential-mode EMI reduction in a multiphase DCM flyback converter
Switched converters are a source of electromagnetic interference (EMI) due to the hard switching and abrupt edges in the current and voltage waveforms. Multiphase converters can reduce the EMI at the source, minimizing the conducted EMI generation, without changing dramatically the normal operation of the circuit. Input filter can be greatly reduced, radiated EMI is lower, and internal EMI problems are minimized. This paper is focused on exploring multiphase converters as a topological technique to reduce conducted differential-mode EMI generation at the source, considering some no idealities of the multiphase converter
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Low-voltage switched-capacitor circuits
In recent years, the rapidly growth of CMOS technology has evolved towards submicron and deep-submicron features. Due to smaller device sizes, and significant demand for low-power designs, the maximum allowable power supply voltage is restricted. So far, two solutions; clock boosting and switched opamp schemes have been proposed. The material presented in this thesis shows the drawback of these schemes while presenting three new methods for realizing low-voltage switched-capacitor integrators which are the key stages of Îâ modulators and SC filters.
Using these integrators, several circuit realizations of SC filters and second order Îâ modulators will be shown
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