Atul Kumar

Bio: Atul Kumar is an academic researcher from Jaypee Institute of Information Technology. The author has contributed to research in topics: Current conveyor & Operational transconductance amplifier. The author has an hindex of 11, co-authored 38 publications receiving 285 citations.

Novel CMOS Dual-X Current Conveyor Transconductance Amplifier Realization with Current-Mode Multifunction Filter and Quadrature Oscillator

Abstract: This paper presents a novel active element, namely dual-X current conveyor transconductance amplifier. The CMOS implementation, parasitic model and characteristic performance parameters of the proposed dual-X current conveyor transconductance amplifier have been explored. The proposed active element has the advantages of good operational bandwidth, good dynamic range and low power consumption. Additionally, current-mode multifunction filter and quadrature oscillator are proposed to examine the applicability of the newly proposed active element. The proposed current-mode multifunction filter provides the responses, low-pass, high-pass and band-pass simultaneously without any circuit modification. The proposed quadrature oscillator circuit simultaneously generates three current outputs and three voltage outputs. The non-ideal analyses of both current-mode multifunction filter and quadrature oscillator are also included. Moreover, the active and passive sensitivities of both current-mode multifunction filter and quadrature oscillator are calculated which are found to be less than unity in magnitude. HSPICE simulation results are depicted to confirm the theoretical analyses. Moreover, practicality of novel dual-X current conveyor transconductance amplifier is examined through the experimental results of the proposed quadrature oscillator.

Low Voltage Operated Current-Mode First-Order Universal Filter and Sinusoidal Oscillator Suitable for Signal Processing Applications

Abstract: This paper introduces a current-mode first-order universal filter which is realized using single modified dual-X current conveyor transconductance amplifier and two capacitors only. The circuit configuration is appropriate to monolithic integration. The circuit enjoys benefits of low input and high output impedances making the circuit easily cascadable, electronically tunable pole frequency and low operating supply voltages. The non-ideal and parasitic analyses of the circuit are explored. The cascadability of proposed first-order filter is verified by realizing a second-order all-pass filter. Additionally, one application of proposed first-order universal filter in terms of voltage-mode sinusoidal oscillator is also presented. The oscillator circuit provides two 180° out of phase voltage signals, simultaneously. The output voltage signals are obtainable from low impedance terminals. To validate the proposed circuits, HSPICE simulations are done. Moreover, to explore the practical aspects of proposed circuits, experimental results of first-order universal filter for all-pass function and second-order all-pass filter, are carried out by using commercially available ICs.

Electronically Tunable First-Order Filters and Dual-Mode Multiphase Oscillator

Abstract: This paper introduces two novel circuits of first-order universal filter that comprise single multiple outputs dual-X current conveyor transconductance amplifier and one grounded capacitor only. The first circuit is of current-mode type, and second is of transadmittance-mode type. Both the circuits are suitable to modern IC technology and offer the feature of ease of cascadability. The proposed circuits do not need any passive component matching constraints. Moreover, the pole frequency of both the circuits is electronically tunable. The transadmittance-mode type circuit also provides an interesting feature of electronic and independent tuning of amplitudes of output currents without affecting the pole frequency. To check the applicability of the proposed circuit, a dual-mode multiphase oscillator is also derived from the proposed transadmittance-mode type filter. It provides two quadrature voltage outputs and four quadrature current outputs simultaneously. The oscillation frequency and condition of oscillation are orthogonally and electronically controllable. The non-ideal and parasitic analyses of all the proposed circuits are investigated, and HSPICE simulation results are depicted to confirm the proposed theory. Furthermore, transadmittance-mode type first-order universal filter is experimentally verified using commercially available ICs.

A fully electronically controllable Schmitt trigger and duty cycle-modulated waveform generator

Abstract: Summary The paper introduces a new Schmitt trigger consisting of only one multiple-output current inverting differential input transconductance amplifier with no passive element. The proposed circuit is simple and usable up to 100 MHz with the advantage of electronically controlled threshold levels and amplitude of the output. The circuit is also little sensitive to temperature and benefits from low power dissipation (0.5 mW). The amplitude of the output current is tunable electronically from 5 nA to 500 μA, which is a wide tunable range. The effects of transistors mismatch on proposed Schmitt trigger have also been explored. The utility of the proposed circuit is further justified through its application as a triangular/square wave generator, with a maximum frequency of 75 MHz. Duty cycle modulation through electronic means is also shown for the generator circuit, where duty cycle results for 80, 20, and 95% have been included, by varying external control current. The cadence VIRTUOSO simulation results by using generic process design kit 90-nm technology are shown to confirm the proposed theory. The proposed circuits are also verified through experimental results by using commercial integrated circuits: AD844 and LM13700. All the simulated and experimental results promise potential applications of the proposed circuits in instrumentation and communication systems. Copyright © 2017 John Wiley & Sons, Ltd.

Novel CMOS MO-CFDITA based fully electronically controlled square/triangular wave generator with adjustable duty cycle

Abstract: This study presents a novel square/triangular wave generator based on multiple-output current follower differential input transconductance amplifier (MO-CFDITA) with reduced complexity in terms of transistors. The proposed generator comprises of single MO-CFDITA and one grounded capacitor only which makes the proposed generator circuit suitable to integrated circuit implementation. The proposed generator provides output square wave in current mode and output triangular wave in voltage mode. The amplitude of current-mode square wave is electronically and independently tunable via bias current. The DC level of the triangular wave is also electronically adjustable. The proposed generator has dual-slope operation and its duty cycle is adjustable with the help of DC current source over a range of 5–95%. The proposed generator consumes a power of 1.45 mW only and it is usable up to 50 MHz which is quite good operating frequency range. To examine the performance of the proposed generator, the cadence VIRTUOSO simulation results have been depicted. Additionally, the simulation results and performance parameters of complementary metal–oxide–semiconductor (CMOS) MO-CFDITA are included. The practicality of the proposed generator is verified through the experimental results.

Optimized Hybrid PWM Scheme for Mitigating Zero-Crossing Distortion in Totem-Pole Bridgeless PFC

Abstract: A totem-pole bridgeless power factor corrector has been widely used in high-power ac–dc power conversion for its low component count and high energy efficiency. Its active bridge is configured to operate the power circuit as a synchronous boost converter over the line cycles. However, due to some intrinsic and extrinsic factors, input current distortion near the zero crossings is unavoidable. A hybrid pulsewidth modulation (PWM) scheme for mitigating such zero-crossing distortion is proposed. The concept is based on changing the PWM modulation schemes dynamically around the zero crossings, so that the line current can still be profiled with a switching scheme that does not require tracking the polarity of the grid voltage accurately. A generalized model for describing the variation of the inductor current, which is also the input current, from its average value in a switching cycle is formulated and is used to derive the optimal alignment of the PWM pulses for giving the smallest transient variation upon changing the modulation scheme. Results indicate that the voltage pulses generated by the active bridge are preferably symmetrical and center aligned in a switching period. A 1-kW 85–265-Vac/400-Vdc 47–63-Hz SiC-based prototype has been built and evaluated.

Novel CMOS Dual-X Current Conveyor Transconductance Amplifier Realization with Current-Mode Multifunction Filter and Quadrature Oscillator

Abstract: This paper presents a novel active element, namely dual-X current conveyor transconductance amplifier. The CMOS implementation, parasitic model and characteristic performance parameters of the proposed dual-X current conveyor transconductance amplifier have been explored. The proposed active element has the advantages of good operational bandwidth, good dynamic range and low power consumption. Additionally, current-mode multifunction filter and quadrature oscillator are proposed to examine the applicability of the newly proposed active element. The proposed current-mode multifunction filter provides the responses, low-pass, high-pass and band-pass simultaneously without any circuit modification. The proposed quadrature oscillator circuit simultaneously generates three current outputs and three voltage outputs. The non-ideal analyses of both current-mode multifunction filter and quadrature oscillator are also included. Moreover, the active and passive sensitivities of both current-mode multifunction filter and quadrature oscillator are calculated which are found to be less than unity in magnitude. HSPICE simulation results are depicted to confirm the theoretical analyses. Moreover, practicality of novel dual-X current conveyor transconductance amplifier is examined through the experimental results of the proposed quadrature oscillator.

Low Voltage Operated Current-Mode First-Order Universal Filter and Sinusoidal Oscillator Suitable for Signal Processing Applications

Abstract: This paper introduces a current-mode first-order universal filter which is realized using single modified dual-X current conveyor transconductance amplifier and two capacitors only. The circuit configuration is appropriate to monolithic integration. The circuit enjoys benefits of low input and high output impedances making the circuit easily cascadable, electronically tunable pole frequency and low operating supply voltages. The non-ideal and parasitic analyses of the circuit are explored. The cascadability of proposed first-order filter is verified by realizing a second-order all-pass filter. Additionally, one application of proposed first-order universal filter in terms of voltage-mode sinusoidal oscillator is also presented. The oscillator circuit provides two 180° out of phase voltage signals, simultaneously. The output voltage signals are obtainable from low impedance terminals. To validate the proposed circuits, HSPICE simulations are done. Moreover, to explore the practical aspects of proposed circuits, experimental results of first-order universal filter for all-pass function and second-order all-pass filter, are carried out by using commercially available ICs.