New Realization of Quadrature Oscillator using OTRA

In this paper a new, operational transresistance amplifier (OTRA) based, third order quadrature oscillator (QO) is presented. The proposed structure forms a closed loop using a high pass filter and differentiator. All the resistors employed in the circuit can be implemented using matched transistors operating in linear region thereby making the proposed structure fully integrated and electronically tunable. The effect of non-idealities of OTRA has been analyzed which suggests that for high frequency applications self-compensation can be used. Workability of the proposed QO is verified through SPICE simulations using 0.18μm AGILENT CMOS process parameters. Total harmonic distortion (THD) for the proposed QO is found to be less than 2.5%.The sensitivity, phasenoise analysis is also discussed for the proposed structure

Operational transresistance amplifier based PID controller

This paper presents Operational transresistance amplifier (OTRA) based proportional-integral- derivative (PID) controller with independent electronic tuning of proportional, integral, and derivative constants. The configuration can be made fully integrated by implementing the resistors using matched transistors operating in the linear region. Theoretical propositions are verified through SPICE simulations using 0.18 µm process parameters from MOSIS (AGILENT). In order to demonstrate the workability of the proposed controller, its effect on step response of an OTRA based second order system is analyzed and presented

Spasticity Outcome Tools in Traumatic Complete Spinal Cord Injury

Objective: To evaluate spasticity in patients of complete motor complete spinal cord injury using M.A.S ,SCATS and PSFS tools of spasticity and assessing their correlation. Design:  Observational cross-sectional study. Setting:  In-patient rehabilitation ward. Participants: 50 individuals of chronic (≥ 1 year trauma) motor complete SCI were classified into mild (n=16), moderate (n=11), and severe (n=23) spastic groups; based on their lower limb extensor muscle group spasticity score using a Modified Ashworth Scale (M.A.S), Spinal cord assessment tool for spastic reflexes(SCATS) and Penn spasm frequency scale (PSFS).  Main Outcome Measures: The proportion of cases in mild, moderate, severe spastic groups, mean MAS score, mean SCATS Score and PSFS Score were evaluated and were compared between the groups with different grades of spasticity. Results:  The mean M.A.S score among the study group was 3.71±1.60. The mean SCAT ankle clonus score, flexor spasm score and extensor spasm score were 1.55±1.05, 1.36±0.81 and 1.22±0.76 respectively (P<0.001S).The mean PSFS (frequency) score and mean PSFS (severity) score was 1.78±0.84 and 1.56±0.70 respectively( P<0.001S). All the three spasticity  outcome tools were found to be significantly associated with the type of spasticity (P≤0.001).A significant positive correlation was observed between M.A.S score and the mean PSFS (FREQ; r = 0.856) score and PSFS (SEV; r = 0.818) score and the mean SCAT score(r=0.913).  Conclusion: All three spasticity outcome tools M.A.S, PSFS and SCATS are acceptable as well as feasible, inherit good clinical utility and correlate significantly with the severity of spasticity. Significant correlations were observed between SCATS score and PSFS score with the M.A.S score. No single outcome measure can reflect the multidimensional nature of spasticity; hence a battery of tests should be applied to measure spasticity to plan antispasmodic treatment in such patients. Keywords: Spinal cord injury, Spasticity, Modified Ashworth score, Spinal cord assessment tool for spastic reflexes, Penn spasm frequency scale

A Class of Differentiator-Based Multifunction Biquad Filters Using OTRAs

This paper presents Signal Flow Graph (SFG) approach-based realization of Single Input Multiple Output (SIMO) filter topologies. A differentiator is placed as basic building block. A total of sixteen variants are derived from the proposed differentiator-based SFG. The Operational Trans-Resistance Amplifier (OTRA), an active block having low parasitics at input terminals, is used to validate the proposed methodology. All the derived filter structures use three OTRAs, six resistors and two capacitors. The filter performance parameters can be adjusted independently. The functional verification of the proposed method is done via SPICE simulations using 0.18 μm CMOS technology parameters from MOSIS

Realization of DVCCTA Based Versatile Modulator

A Differential Voltage Current Conveyor Transconductance Amplifier (DVCCTA) based versatile modulator is proposed which can work as an amplitude modulator, frequency modulator, delta modulator, and sigma delta modulator. The modulator operational scheme uses pulse generator as a core and its output is used as carrier signal. A DVCCTA based pulse generator is proposed first and subsequently configured as different modulators. Compact realization is the key feature of the proposed circuit as it uses two DVCCTA; a grounded resistor and a grounded capacitor hence are appropriate for IC realization. The functionality of the proposed circuit is verified through SPICE simulations using TSMC 0.25 μm CMOS process model parameters. The performance parameters such as power dissipation and noise for various modulator schemes are also obtained

Harmful and beneficial aspects of Parthenium hysterophorus: an update

Parthenium hysterophorus is a noxious weed in America, Asia, Africa and Australia. This weed is considered to be a cause of allergic respiratory problems, contact dermatitis, mutagenicity in human and livestock. Crop production is drastically reduced owing to its allelopathy. Also aggressive dominance of this weed threatens biodiversity. Eradication of P. hysterophorus by burning, chemical herbicides, eucalyptus oil and biological control by leaf-feeding beetle, stem-galling moth, stem-boring weevil and fungi have been carried out with variable degrees of success. Recently many innovative uses of this hitherto notorious plant have been discovered. Parthenium hysterophorus confers many health benefits, viz remedy for skin inflammation, rheumatic pain, diarrhoea, urinary tract infections, dysentery, malaria and neuralgia. Its prospect as nano-medicine is being carried out with some preliminary success so far. Removal of heavy metals and dye from the environment, eradication of aquatic weeds, use as substrate for commercial enzyme production, additives in cattle manure for biogas production, as biopesticide, as green manure and compost are to name a few of some other potentials. The active compounds responsible for hazardous properties have been summarized. The aim of this review article is to explore the problem P. hysterophorus poses as a weed, the effective control measures that can be implemented as well as to unravel the latent beneficial prospects of this weed

Current Mode Full-Wave Rectifier Based on a Single MZC-CDTA

This paper presents a current mode full-wave rectifier based on single modified Z copy current difference transconductance amplifier (MZC-CDTA) and two switches. The circuit is simple and is suitable for IC implementation. The functionality of the circuit is verified with SPICE simulation using 0.35 μm TSMC CMOS technology parameters

Single VDTA Based Dual Mode Single Input Multioutput Biquad Filter

This paper presents a dual mode, single input multioutput (SIMO) biquad filter configuration using single voltage differencing transconductance amplifier (VDTA), three capacitors, and a grounded resistor. The proposed topology can be used to synthesize low pass (LP), high pass (HP), and band pass (BP) filter functions. It can be configured as voltage mode (VM) or current mode (CM) structure with appropriate input excitation choice. The angular frequency (ω0) of the proposed structure can be controlled independently of quality factor (Q0). Workability of the proposed biquad configuration is demonstrated through PSPICE simulations using 0.18 μm TSMC CMOS process parameters

Capacitance Characteristics Behavior of 0.5 Order FC Using CFOA Based FC Multiplier

his paper presents a method for capacitance scaling of Fractional Capacitor (FC) which is implemented using Current Feedback Operational Amplifiers (CFOA) based Capacitance Multipliers (C Multipliers). The circuit facilitates the change in FC value without changing component values in R-C network used for FC modelling or fabricating a new FC. The performance of the proposed circuit is examined for non ideal effects of CFOA. Effective impedance of scaled FC is examined through MATLAB simulations. The functionality of the realized scalers is verified using SPICE simulations where the FC is modelled using domino RC ladder network. Simulation results for impedance magnitude and phase responses are presented for various scaling factors and are compared with theoretical counterparts. The circuit application of proposed FC scaler is demonstrated through implementation of fractional order lossy and lossless integrators; and may be extended to fractional order filters, oscillators, controllers etc