Current Issue : October - December Volume : 2011 Issue Number : 1 Articles : 6 Articles
A generic design (GD) for realizing an nth order log-domain multifunction filter (MFF), which can yield four possible stable filter configurations, each offering simultaneously lowpass (LP), highpass (HP), and bandpass (BP) frequency responses, is presented. The features of these filters are very simple, consisting of merely a few exponential transconductor cells and capacitors; all grounded elements, capable of absorbing the shunt parasitic capacitances, responses are electronically tuneable, and suitable for monolithic integration. Furthermore, being designed using log-domain technique, it offers all its advantages. As an example, 5th-order MFFs are designed in each case and their performances are evaluated through simulation. Lastly, a comparative study of the MFFs is also carried, which helps in selecting better high-order MFF for a given application....
The paper presents a new current mode biquadratic filter with one input and three outputs using differential voltage current conveyor (DVCC) and four passive components. The proposed circuit can simultaneously realize low-pass, band-pass, and high-pass filter functions without changing the circuit topology and passive elements. The circuit exhibits a good frequency performance and low-sensitivity figures. PSPICE simulation using 0.5?�µm CMOS parameters are given to validate the proposed circuit. The circuit provides a simple yet novel solution to the current-mode filtering after appropriate incorporation of current sensing elements in form of current buffers....
This paper reports on the integration of an optical protein with single electron transistors to form a nano-bio-hybrid device for sensing. Bacteriorhodopsin (bR) is an optoelectric protein that translocates a proton across a distance of several nanometers in response to an absorbed photon of incident light. This charge gradient results in a measurable voltage in the dried state. Single electron transistors (SETs) have active regions consisting of one or more quantum islands with a size typically 10 nanometers or less. Integrating bacteriorhodopsin with the gate of a SET provides a device capable of a modulated electrical output in response to optical modulation at the device gate. Modulation of the optoelectric activity of the bR by chemical binding with a targeted environmental antigen can form a direct chemical-to-electrical sensor reducing the size and complexity of fluorescence-based systems. The work resulted in electrical resistance and capacitance characterization of purple membrane containing bR under variable illumination to ensure minimal impact on SET operation. Purple membrane containing bacteriorhodopsin was electrodeposited on the SET gates, and current throughput was well correlated with variable and cyclic illumination. It was confirmed that bR optoelectric activity is capable of driving SETs....
This paper reports two new circuit topologies using second-generation current conveyors (CCIIs) for realizing variable frequency sinusoidal oscillators with minimum passive components. The proposed topologies in this paper provide new realizations of resistance-controlled and capacitor-controlled variable frequency oscillators (VFOs) using only four passive components. The first topology employs three CCIIs, while the second topology employs two CCIIs. The second topology provides an advantageous feature of frequency tuning through two grounded elements. Application of the proposed circuits as a wide-frequency range digitally controlled sinusoid generator is exhibited wherein the digital frequency control has been enabled by replacing both the capacitors by two identical variable binary capacitor banks tunable by means of the same binary code. SPICE simulations of the CMOS implementation of the oscillators using 0.35?�µm TSMC CMOS technology parameters and bipolar implementation of the oscillators using process parameters for NR200N-2X (NPN) and PR200N-2X (PNP) of bipolar arrays ALA400-CBIC-R have validated their workability. One of the oscillators (with CMOS implementation) is exemplified as a digitally controlled sinusoid generator with frequency generation from 25?kHz to 6.36?MHz, achieved by switching capacitors and with power consumption of 7?mW in the entire operating frequency range....
A new active circuit is proposed for the realisation of lossless grounded and floating inductance employing Voltage Differencing Differential Input Buffered Amplifiers (VD-DIBAs). The proposed grounded simulated inductance circuit employs two VD-DIBAs and a single-grounded capacitor whereas the floating simulated inductance circuit employs three VD-DIBAs and a grounded capacitor. The circuit for grounded inductance does not require any realization conditions whereas in case of floating inductance, only equality of two transconductances is needed. Some sample results demonstrating the applications of the new simulated inductors using VD-DIBAs have been given to confirm the workability of the new circuits....
A systematic synthesis procedure for generating second-order grounded passive element canonic oscillators is given. The synthesis procedure is based on using nodal admittance matrix (NAM) expansion with the bracket method as well as using the infinity parameters. The resulting derived oscillators include circuits using various types of current conveyors. Two classes of oscillators are considered in this paper, and they have the advantages of having independent control on the condition of oscillation and on the frequency of oscillation by varying two different grounded resistors. The two classes of oscillators considered can be easily compensated for the parasitic element effects introduced by the current conveyors. This paper is considered to be continuation to the recently published paper on oscillators using NAM expansion D. G. Haigh et al. (2006). This is the first paper in the literature which uses limit-variables called infinity-variables D. G. Haigh et al. (2005) in the synthesis of oscillator circuits. Simulation results demonstrating the practicality of some of the generated circuits are included....
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