Xianyang, China

Time filter

Source Type

Li Y.-A.,Xianyang Normal University
AEU - International Journal of Electronics and Communications | Year: 2012

The paper presents a series of basic circuits based on CFTAs (current follower transconductance amplifier), which contain amplifier, lossless integrator, first-order universal current-mode filter, simulation resistor, negative resistance converter, gyrator, capacitor multiplier, and frequency-dependent negative resistance circuit. Having used canonic number of grounded capacitors and resistors, the circuits are easy to be integrated and the parameters of the circuits can be adjusted electronically by tuning bias currents of the CFTAs. It is noted that the results of circuit simulations are in agreement with theory. © 2012 Published by Elsevier GmbH. All rights reserved.


Li Y.,Xianyang Normal University
AEU - International Journal of Electronics and Communications | Year: 2012

This paper presents a new current-mode Wien-bridge oscillator with automatic amplitude control. The oscillator only employs single MCCCDTA as the active element and provides two current outputs with small distortion from high output impedances. Its oscillation condition and frequency can be tuned electronically, linearly and independently through tuning bias currents of MCCCDTA. The circuit simulation results are in agreement with theory. © 2011 Elsevier GmbH All rights reserved.


Li Y.,Xianyang Normal University
International Journal of Electronics | Year: 2012

This article presents a novel current-mode multiphase sinusoidal oscillator. The oscillator can produce two groups of n output currents and one group of 2n output currents (n being even or odd) with equal amplitude and equal-phase space. The circuit only uses one multi-output current differencing transconductance amplifier and one grounded capacitor for each section, and is easy to integrate. Its oscillation condition and frequency can be electronically tuned linearly and independently, and its outputs possess high impedance. It is important that the multi-frequency oscillation in the oscillator is studied and a method for eliminating unnecessary oscillation is given. In addition, the inverting amplifier with the automatic gain control is employed to reduce the distortion of output signals. Finally, the frequency error is analysed and the simulated results are illustrated. © 2012 Copyright Taylor and Francis Group, LLC.


Li Y.-A.,Xianyang Normal University
AEU - International Journal of Electronics and Communications | Year: 2013

This paper presents a NAM expansion method for systematically synthesizing OTA-based floating gyrators. After describing nullor-mirror components of OTAs, class I, II and III gyrators, which can be built with standard OTAs, are synthesized by using the nullor-mirror equivalent models described by NAM. The class-I gyrators employing two DO-OTAs have four equivalent realizations, the class-II gyrators employing three SO-OTAs have eight equivalent realizations, and the class-III gyrators employing four SISO-OTAs have 16 equivalent realizations. Having used canonic number of components, the circuits are easy to be integrated and their parameters can be tuned electronically through tuning bias currents of OTAs. Finally, as an example, the MULTISIM simulation results of a notch filter constructed by the OTA-based III gyrator are presented to verify the realizability of the derived circuits. © 2012 Elsevier GmbH. All rights reserved.


Li Y.-A.,Xianyang Normal University
AEU - International Journal of Electronics and Communications | Year: 2013

A NAM expansion method for systematic synthesis of OTA-based Wien oscillators is given. Moreover, the NAM expansion method for four different classes of the oscillators is considered. The class I oscillators employ three OTAs, the class II oscillators employ four OTAs, the class III oscillators employ five OTAs, and the class IV oscillators employ six OTAs. Each class has 32 different forms, resulting in 128 Wien oscillators using OTAs. Having used grounded capacitors, the circuits are easy to be integrated and their parameters can be tuned electronically through tuning bias currents of the OTAs. The MULTISIM simulation results have been included to support the generation method. © 2013 Elsevier GmbH.


Li Y.A.,Xianyang Normal University
Analog Integrated Circuits and Signal Processing | Year: 2015

This paper presents a nodal admittance matrix expansion method for systematically synthesizing floating gyrators using current controlled current conveyor transconductance amplifiers (CCCCTAs). After describing nullor–mirror models of the CCCCTAs, class I and II gyrators are synthesized by means of NAM expansion method. The class I gyrators employing a CCCCTA and a current-controlled current conveyor have 16 equivalent realizations, and the class II gyrators employing two CCCCTAs have 24 equivalent realizations. Having used canonic number of components, the circuits are easy to be integrated and their parameters can be electronically tuned through tuning bias currents of CCCCTAs. Finally, as an example, the MULTISIM simulation results of a notch filter constructed by using a class II gyrator are presented to verify the realizability of the derived circuits. © 2014, Springer Science+Business Media New York.


Li Y.,Xianyang Normal University
Radioengineering | Year: 2010

This paper presents a modified current differencing transconductance amplifier (MCDTA) and a MCDTA based quadrature oscillator. The oscillator is current-mode and provides current output from high output impedance terminals. The circuit uses only one MCDTA and two grounded capacitors, and is easy to be integrated. Its oscillation frequency can be tuned electronically by tuning bias currents of MCDTA. Finally, frequency error is analyzed. The results of circuit simulations are in agreement with theory.


Li Y.,Xianyang Normal University
Circuits, Systems, and Signal Processing | Year: 2011

This paper presents a modified current differencing transconductance amplifier (MCDTA) and the MCDTA based KHN filter with high output impedance. Moreover, the paper gives a current-mode sixth-order elliptic band-pass filter by means of cascade method. The filter with only three MCDTAs, six grounded capacitors and four resistors is easy to be integrated. Its pole frequency can be determined electronically through adjusting bias currents of MCDTA. The results of circuit simulations are in agreement with the designed parameters. © 2011 Springer Science+Business Media, LLC.


Li Y.,Xianyang Normal University
Radioengineering | Year: 2011

In this paper, a modified CDTA (MCDTA) is presented and the current-mode second-order band-pass, high-pass notch, and low-pass notch circuits using MCDTAs are given. Moreover, a current-mode sixth-order elliptic band-pass filter is realized by means of cascade method. Having used six MCDTAs, one CDTA, six grounded capacitors and two resistors, the circuit is easy to be integrated, of which the parameters can be electronically adjusted by tuning bias currents. It is noted that the results of circuit simulations are in agreement with theory.


Li Y.-A.,Xianyang Normal University
Journal of Circuits, Systems and Computers | Year: 2013

According to the terminal relations of the DO-OTA, eight nullor-mirror models for the DO-OTA are presented in this paper, Moreover, the NAME method for two different classes of T-T filters is considered. The class I filters, employing three SISO-OTAs, have 16 different forms, and the class II filters, employing one SISO-OTA and one DISO-OTA or one SIDO-OTA, have eight different forms. Due to use of canonic number of components, the circuits are easy to be integrated and their parameters can be tuned electronically through tuning bias currents of the OTAs. The MULTISIM simulation results have been included to verify the workability of the derived circuit. © 2013 World Scientific Publishing Company.

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