Voltage-controlled filter

About: Voltage-controlled filter is a research topic. Over the lifetime, 5514 publications have been published within this topic receiving 70872 citations. The topic is also known as: VCF.

Frequency agile duplex filter

Abstract: Systems and methods are disclosed for an electronically adjustable signal filter system, which comprises, in some embodiments, a first filter coupled to an antenna coupling network and a second filter, a power amplifier coupled to the first filter, an antenna connected to an antenna coupling network, a pilot tone generator coupled to the first filter, and a first signal source connected to the power amplifier and first filter. In some embodiments, the power amplifier amplifies the first signal, the first filter places a notch into the first signal transmitted to the antenna coupling network, the antenna coupling network combines the first signal and a second signal received from the antenna and transmits a third signal to the second filter.

Removal of high frequency noise from ECG signal using digital IIR butterworth filter

Abstract: ECG is the main tool used by the physicians for identifying and for interpretation of Heart condition. The ECG should be free from noise and of good quality for the correct diagnosis. In real time situations ECG are corrupted by many types of artifacts. The high frequency noise is one of them. The present paper deals with removing of noise from ECG of high frequency contents with help of Low pass digital filter of the cutoff frequency 100Hz. The sampling period used is .001sec. The filter is designed with Butterworth Approximations. The results of before filtration and after filtration are depicted in the paper. Paper contains detail design of the digital Butterworth filter and its realization. The experimentation is performed on the database generated in Laboratory. The simulation results show the filter works satisfactorily with some modifications in PQRST waveform.

A Compact Ultra-Wideband (UWB) Bandpass Filter With Transmission Zero

Abstract: A compact ultra-wideband (UWB) bandpass filter with a fractional bandwidth (FBW) of about 110% and transmission zero at the high frequency edge is presented using a microstrip structure. The filter is based on a circuit model for an optimum stub filter consisting of only 5 short-circuited stubs separated by non-redundant connecting lines. As a result, the filter in a compact structure exhibited a selective filtering characteristic equivalent to a 9-pole Chebyshev filter. The design was successfully realized in theory and verified by full-wave EM simulation of the full layout and the experiment. The proposed filter had low insertion loss, sharp rejection, and excellent performance both inside and outside the band.

New Universal Filter with One Input and Five Outputs Using Current-Feedback Amplifiers

Abstract: A new universal voltage-mode second-order filter circuit is presented. The circuit uses five current-feedback operational amplifiers, two grounded capacitors three grounded resistors and three floating resistors. The circuit can realize all the standard filter functions; lowpass, highpass, bandpass, notch and allpass, without changing the passive elements. The proposed circuit enjoys independent grounded-resistance-control of the natural frequency and the bandwidth, low output impedances, high input impedance as well as low active and passive sensitivities.