1. Faculty Publications
Permanent URI for this communityhttps://idr.l2.nitk.ac.in/handle/1/5
Browse
Item A 0.3-V, 2.4-nW, and 100-Hz fourth-order LPF for ECG signal processing(2020) Rao G. H.; Sreenivasulu P.; Rekha S.; Bhat M.S.An ultra-low voltage, low power bulk-driven voltage follower (VF) is proposed in this paper. Further, it is exploited to design a fourth-order low-pass filter (LPF) for electrocardiogram (ECG) signal processing. The filter is designed in UMC 180-nm CMOS technology and operates with an ultra-low supply voltage of 0.3 V. It consumes an extremely low power of 2.4 nW for a cutoff frequency of 100 Hz. Results of post-layout simulation show that the proposed filter provides a dynamic range (DR) of 51.6 dB even from a 0.3-V supply voltage. The filter achieves a Figure-of-merit (FoM) of 4.7 × 10−15, which is better than many designs listed in the literature. © 2020 John Wiley & Sons, Ltd.Item A 0.3?V, 56?dB DR, 100?Hz fourth order low-pass filter for ECG acquisition system(2019) Sreenivasulu, P.; Hanumantha, Rao, G.; Rekha, S.; Bhat, M.S.This paper proposes an extremely low voltage, low power bulk-driven voltage follower (BD-VF). As an application of the proposed BD-VF, a 4th order low-pass filter (LPF) with cutoff frequency adjustable from 50 Hz to 250 Hz is designed for electrocardiogram (ECG) acquisition systems. The filter is implemented in UMC 180 nm CMOS technology occupying only 0.03 mm2 area. Post layout simulation results show that the filter offers 56 dB dynamic range even with an extremely low supply voltage of 0.3 V. The total power consumption of the filter is 4.8 nW for a cutoff frequency of 100 Hz. The Figure-of-merit (FoM) and capacitance/pole of the filter are 5.7 10?15 and 2.2 pF respectively. The proposed filter offers the lowest FoM compared to the state-of-the-art nW-class filters. 2019 Elsevier LtdItem A 0.5 V, 1 nA Switched Capacitor PTAT Current Reference Circuit(2019) Hanumantha, Rao, G.; Rekha, S.This paper presents a low voltage, low power Proportional to Absolute Temperature (PTAT) current reference circuit. Switched capacitor is used instead of a large resistor, which in turn reduces the area of the circuit and makes the circuit less process sensitive. The proposed circuit has been designed using UMC 65 nm CMOS technology and simulated in Cadence Virtuoso. It generates a reference current (Iref) of 1 nA at 0.5 V supply voltage (Vdd) at room temperature (27�C) and follows PTAT characteristics in the temperature range of -10�C to 80�C. The total power consumption of the circuit is as low as 1.5 nW. The supply voltage sensitivity of Iref is 2.7 %/V, which shows that the proposed circuit is less sensitive to supply voltage variations. Index Terms - Low voltage, Low power, PTAT current, Switched capacitor. � 2019 IEEE.Item A 0.5 V, 20 ?w pseudo differential 500 kHz Gm-C low pass filter in 0.18 ?m CMOS technology(2012) Harishchandra, V.M.; Laxminidhi, T.Scaling of supply voltage due to shrinking in the device sizes has lead to bulk driven circuit techniques specially for analog circuits that operate at low supply voltages. In this paper we present a bulk driven pseudo differential low power, continuous time Cochlea 2 nd order Butterworth low pass filter operating at a supply voltage of 0.5 V. The filter uses Gm-C technique in 0.18 ?m n-well standard CMOS process and has a bandwidth of 500 kHz. Simulations results have shown that the filter offers a dynamic range of 48 dB while consuming a power of 20 ?W. Simulated Figure of Merit (FOM) is found to be 0.52 fJ and is found to be the lowest among similar low voltage filters found in literature. The percentage change in transconductance is less than ?5% for temperature variation of 0-70�C at 0.5 V supply voltage and across five process corners. � 2012 IEEE.Item 0.5 V, 36?W Gm-C butterworth low pass filter in 0.18?m CMOS process(2012) Harishchandra, V.M.; Laxminidhi, T.This paper presents a low voltage, low power continuous-time (G m-C) 4th order low pass Butterworth filter with a 3-dB bandwidth of 1MHz and capable of operating at supply voltage as low as 0.5V in 0.18 ?m. The filter uses bulk-driven technique for achieving the necessary head-room. The simulation results show that the filter has a peak-to-peak signal swing of 1.2V (differential) for 1% THD and a dynamic range of 54 dB. The power consumed by the filter is 36?W when operating at a voltage of 0.5 V. The Figure of Merit (FOM) achieved by the filter is 0.05 fJ and is found to be lowest among the similar filters found in the literature. � 2012 IEEE.Item 0.5 V, low power, 1 MHz low pass filter in 0.18 ?m CMOS process(2012) Vasantha, M.H.; Laxminidhi, T.In this paper a low power continuous-time 4th order low pass Butterworth filter operating at power supply of 0.5 V is presented. A 3-dB bandwidth of 1 MHz using technology node of 0.18 ?m is achieved. In order to achievenecessary head-room, the filter uses pseudo-differential bulk-driven transconductor. A master-slave based common modefeedback(CMFB) circuit sets the output common mode voltageof transconductor. The simulation results show that the filter has a dynamic range of 54 dB and consumes a total power of 36 ?W when operating at a supply voltage of 0.5 V. The Figure of Merit (FOM) achieved by the filter is 0.05 fJ, lowest among similar low-voltage filters found in the literature. The simulation result show that the 3-dB bandwidth variation for process, voltage and temperature is less than �10%. � 2012 IEEE.Item A 0.5V 300?W 50MS/s 180nm 6bit Flash ADC using inverter based comparators(2012) Komar, R.; Bhat, M.S.; Laxminidhi, T.This paper presents a 0.5 V, 50 MS/s, 6 bit Flash ADC designed using 180 nm CMOS technology. To reduce the silicon area and power requirement, an inverter based comparator is used in the design. Low threshold MOSFETs are used for the ultra low voltage operation. A simple clock delaying technique and back to back inverters in the comparator have been used to increase the power efficiency and speed of operation. A fat tree encoder design is used for digitizing comparator outputs. The measured SNDR at input frequency of 5.1 MHz is 31 dB. The measured maximum INL and DNL for a ramp input are 0.375 LSB and 0.025 LSB, respectively. The design consumes a very low power of 300 ?W. � 2012 Pillay Engineering College.Item A 0.8 V, 5 nA PTAT current reference circuit with improved supply voltage sensitivity(2019) Hanumantha Rao G.; Muhammed Mansoor C.B.; Rekha S.This paper presents a low voltage, low power Proportional to Absolute Temperature (PTAT) current reference circuit with improved supply voltage sensitivity. The proposed circuit is designed and laid out in UMC 65 nm CMOS technology and simulated using Cadence Virtuoso. It generates a reference current (Iref) of 5 nA at 0.8 V supply voltage (Vdd) at room temperature (27°C). Composite transistors are used to improve the supply voltage sensitivity when compared to a traditional beta-multiplier circuit. The current reference circuit consumes a power of 8 nW and follows PTAT characteristics in the temperature range of 0°C to 80°C. The supply voltage sensitivity of Iref is 2.6 %/V, which shows that the proposed circuit is less sensitive to supply voltage variations. © 2019 IEEE.Item A 0.8-V, 55.1-dB DR, 100 Hz Low-Pass Filter with Low-Power PTAT for Bio-Medical Applications(2019) Hanumantha, Rao, G.; Rekha, S.This paper presents a power efficient transconductor-capacitor ((Formula presented.)) filter for front-end processing of bio-medical signals. A low voltage, low-power transconductor with improved output resistance is proposed. It offers a transconductance ((Formula presented.)) of 5.85 nS while operating at a supply voltage ((Formula presented.)) of 0.8 V. Furthermore, a low-power Proportional to Absolute Temperature (PTAT) current reference circuit is designed to bias the transconductor and to make (Formula presented.) independent of temperature. It follows PTAT characteristics in the temperature range of ?20 (Formula presented.) C to 70 (Formula presented.) C and is less sensitive to (Formula presented.) variations. A second-order Butterworth low-pass filter (LPF) with a cutoff frequency of 100 Hz is implemented to validate the proposed transconductor and the PTAT circuit. The filter is designed in UMC 65 nm CMOS process and it takes an area of 0.065 mm (Formula presented.). While consuming a power of 47 nW, it offers a dynamic range (DR) of 55.1 dB. Figure-of-merit (FoM) of the filter is as low as (Formula presented.) J, which is found to be on par with the filters reported in the literature. 2019, 2019 IETE.Item 1,3,4-Trisubstituted pyrazole bearing a 4-(chromen-2-one) thiazole: Synthesis, characterization and its biological studies(2015) Harikrishna, N.; Isloor, A.M.; Ananda, K.; Obaid, A.; Fun, H.-K.A new series 3-{2-[N?-(1,3-disubstituted-1H-pyrazol-4-yl-methylene)-hydrazino]-thiazol-4-yl}-chromen-2-one (10a-l) was synthesized by a multi-step reaction. All the synthesized compounds were characterized by IR, NMR, and mass spectral studies, followed by elemental analysis. The newly synthesized thiazole compounds were screened for their in vitro antibacterial and antifungal studies against various microorganisms. Antimicrobial studies carried out by the well diffusion method, showed a very good zone of inhibition for both bacteria (at a range of 20-50 mm diameter) and fungi (at a range of 10-30 mm diameter). Minimum Inhibitory Concentration (MIC) required for the 100% inhibition of bacteria and fungi was found to be as low as 15.6 ?g ml-1 for a few of the synthesized compounds. The Royal Society of Chemistry 2015.Item 1,5-Dibromo-2,4-dimethoxybenzene(2012) Vijesh, A.M.; Isloor, A.M.; Gerber, T.; Brecht, B.V.; Betz, R.In the title compound, C8H8Br2O2, all non-H atoms lie essentially in a common plane (r.m.s deviation of all fitted non-H atoms = 0.0330 ). In the crystal, weak C-H?O hydrogen bonds connect the molecules, forming chains which extend along the b-axis direction.Item 1-(4-Bromophenyl)-2-(2-chlorophenoxy)ethanone(2012) Shenvi, S.S.; Isloor, A.M.; Gerber, T.; Hosten, E.; Betz, R.In the title compound, C14H10BrClO2, a twofold halogenated derivative of phenylated phenyloxyethanone, the least-squares planes defined by the C atoms of the aromatic rings subtend an angle of 71.31 (17) . In the crystal, C-H?O contacts connect the molecules into chains along the b-axis direction.Item 1-[(3-Benz-yloxy-2-nitro-phen-oxy)meth-yl]benzene(2012) Fun, H.-K.; Arshad, S.; Ubaradka, S.R.; Shetty, P.; Isloor, A.M.The asymmetric unit of the title compound, C20H17NO4, consists of two crystallographically independent mol-ecules. In one of the mol-ecules, the central benzene ring forms dihedral angles of 2.26 (6) and 58.68 (6) with the terminal benzene rings and the dihedral angle between the terminal benzene rings is 56.45 (6) . The corresponding values for the other mol-ecule are 35.17 (6), 70.97 (6) and 69.62 (6) , respectively. In the crystal, an inversion dimer linked by a pair of C-H?O hydrogen bonds occurs for one of the unique mol-ecules. C-H?? and ?-? [centroid-centroid distances = 3.7113 (8) and 3.7216 (7) ] inter-actions link the components into a three-dimensional network.Item 1-[5-Acetyl-2,6-dimethyl-4-(5-phenyl-1H-pyrazol-3-yl)-1, 4-dihydropyridin-3-yl]ethanone monohydrate(2012) Isloor, A.M.; Malladi, S.; Sundershan, S.; Gerber, T.; Hosten, E.; Betz, R.In the title compound, C20H21N3O 2 H2O, the aza-substitued six-membered ring adopts a L4 B conformation. In the crystal, classical N-H?O, N-H?N and O-H?O hydrogen bonds connect the entities into a three-dimensional network. Intramolecular C-H?O contacts are also observed.Item 1-Cyclohexyl-5-(4-methoxyphenyl)-1H-pyrazole-4-carboxy-lic acid(2011) Fun, H.-K.; Quah, C.K.; Chandrakantha, B.; Isloor, A.M.; Shetty, P.In the title compound, C17H20N2O 3, the meth-oxy-phenyl unit is disordered over two sets of sites in a 0.715 (4):0.285 (4) ratio. The pyrazole ring forms dihedral angles of 55.88 (16) and 72.6 (4) with the benzene rings of its major and minor components, respectively. The cyclohexane ring adopts a chair conformation and its C-N bond is in an equatorial orientation. In the crystal, molecules are linked into inversion dimers by pairs of O-H?O hydrogen bonds, generating R 2 2(8) loops..Item 1-Dibromomethyl-4-methoxy-2-nitrobenzene(2009) Fun, H.-K.; Goh, J.H.; Chandrakantha, B.; Isloor, A.M.The asymmetric unit of the title compound, C8H 7Br2NO3, comprises two crystallographically independent molecules (A and B). The nitro groups are twisted from the attached benzene rings, making dihedral angles of 39.26 (9) and 35.90 (9) in molecules A and B, respectively. In each mol-ecule, the dibromo-methyl group is orientated in such a way that the two Br atoms are tilted away from the benzene ring. An inter-esting features of the crystal structure is the two short Br?Br inter-actions which, together with inter-molecular C - H?O hydrogen bonds, link the molecules into an extended three-dimensional network. The crystal structure is further stabilized by weak C - H?? inter-actions. Fun et al. 2009.Item 1-Hexyl-3-Methylimidazolium Chloride-Potassium Carbonate Aqueous Two Phase System: Equilibrium Characteristics and BSA Partitioning Behavior(2014) Regupathi, I.; Monteiro, S.L.The partitioning behavior of the model protein (bovine serum albumin) was investigated in ionic liquid (1-hexyl-3-methylimidazolium chloride) -salt (potassium carbonate) based aqueous two phase system (ATPS). The phase diagram with binodal curve and tie lines for the selected ATPS was developed at different temperatures and analyzed through effective excluded volume (EEV) and Othmer-Tobias and Bancroft equations, respectively. The influence of various process parameters like the ionic liquid and salt concentration, system temperature, tie line length, phase volume ratio, and neutral salt addition on partition coefficient/extraction efficiency of BSA protein was evaluated. 2014 Copyright Taylor & Francis Group, LLC.Item A 1-V 1-GS/s 6-bit low-power flash ADC in 90-nm CMOS with 15.75 mW power consumption(2013) Lad, K.; Bhat, M.S.A 1-V 1-GS/s 6-bit low power flash ADC in 90 nm CMOS technology is presented. Proposed Flash ADC consists of reference generator, comparator array, 1-out-of N code generator, Fat tree encoder and output D-latches. This Flash ADC achieves 5.76 ENOB at Nyquist input frequency without calibration. The measured peak INL and DNL are 0.08LSB and 0.1LSB, respectively. The proposed ADC consumes 15.75 mW from 1V supply and yielding an energy efficiency of 0.291 pJ/conv while operating at 1 GS/s. � 2013 IEEE.Item 1.5�C accurate CMOS temperature sensor with a single point trim at 85�C(2016) Hareesh, P.K.; Laxmindhi, T.This paper presents a temperature sensor with an accuracy of 1.5�C. The paper analyzes inaccuracy of the existing temperature sensors and outlines the techinques to overcome them. The sensor is based on a CMOS current reference which is almost constant over process/corner and voltage variation. Most of the techniques known today for generating a process and voltage independent current source have very stringent constraints on sizing of the transistors. The current source proposed in the paper relaxes such constraints thus easing the portability across various technology nodes. The sensor designed in TSMC 28 nm CMOS process offers the accuracy of 1.5�C over a temperature range of-40�C to 125�C with a single point trim at 85�C. The sensor consumes a power of 90 ?W of power when operating on 1.8 V supply. � 2016 IEEE.Item A 1.8 v 11.02 ?w single-ended inverter-based OTA with 113.62 dB gain(2016) Kaliyath, Y.; Laxminidhi, T.This paper presents a low power 1.8 V single-ended operational trans conductance amplifier (OTA) with a very high dc gain targeted for audio applications. Cascoding and gain boosting are employed to achieve the high gain. The amplifier is implemented in UMC 180 nm CMOS technology. For a typical process corner, the amplifier provides a dc gain of 113.62 dB and a unity gain bandwidth of 2.49 MHz at 62.9� phase margin with capacitive load of 2.5 pF. The amplifier consumes only 6.12 ?A of quiescent current from 1.8 V supply. The amplifier exhibits good performance across all the process corners with the use of body bias technique. � 2016 IEEE.