* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download A very high performance self-biased cascode current mirror for
Mercury-arc valve wikipedia , lookup
Ground (electricity) wikipedia , lookup
Immunity-aware programming wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Stepper motor wikipedia , lookup
Ground loop (electricity) wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Power inverter wikipedia , lookup
History of electric power transmission wikipedia , lookup
Flexible electronics wikipedia , lookup
Electrical substation wikipedia , lookup
Electrical ballast wikipedia , lookup
Electronic engineering wikipedia , lookup
Integrated circuit wikipedia , lookup
Stray voltage wikipedia , lookup
Earthing system wikipedia , lookup
Voltage optimisation wikipedia , lookup
Voltage regulator wikipedia , lookup
Current source wikipedia , lookup
Surge protector wikipedia , lookup
Power electronics wikipedia , lookup
Power MOSFET wikipedia , lookup
Two-port network wikipedia , lookup
Schmitt trigger wikipedia , lookup
Mains electricity wikipedia , lookup
Alternating current wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Buck converter wikipedia , lookup
Wilson current mirror wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Network analysis (electrical circuits) wikipedia , lookup
Analog Integr Circ Sig Process (2013) 75:67–74 DOI 10.1007/s10470-012-9994-5 A very high performance self-biased cascode current mirror for CMOS technology Maneesha Gupta • Bhawna Aggarwal Anil Kumar Gupta • Received: 8 July 2012 / Accepted: 19 November 2012 / Published online: 24 December 2012 Springer Science+Business Media New York 2012 Abstract This paper presents a novel high performance self-biased cascode current mirror (CM) for CMOS technology. The proposed circuit shows a resistance compensated high bandwidth CM operating at low voltages. This circuit uses super cascode configuration to obtain high output impedance required for high performance of CM. Active implementation of passive resistances of the proposed circuit is shown. The simulations of proposed CM are carried out by Mentor Graphics Eldospice based on TSMC 0.18 lm CMOS technology, for input current range of 0–500 lA. A bandwidth of 2.26 GHz, input and output resistances of 679 X and 482 MX respectively, are obtained with a single supply voltage of -1 V. Keywords Low voltage CMOS analog integrated circuits Cascode current mirror High swing operation Self-biased current mirror Super-cascode technique Active implementation 1 Introduction A current mirror (CM) is a circuit designed to carefully generate a true or scaled replica of current flowing through M. Gupta NSIT, Delhi, India e-mail: [email protected] B. Aggarwal (&) MAIT, Delhi, India e-mail: [email protected] A. K. Gupta NIT, Kurukshetra, Haryana, India e-mail: [email protected] one active device, by controlling the current in another active device, regardless of changes in loading. CMs are used as basic building blocks for current amplification, biasing, active loading and level shifting in almost all analog and mixed circuits such as OTAs, CCIIs, OMAs, CFOAs, analog filters etc. Efficient designing of CMs help in improving the overall performance of these systems. The most important parameters of CMs are accuracy, input/ output compliances, input/output impedances, bandwidth and linearity. To improve the CM performance and make it compatible with the present industry trends, various topologies have been suggested earlier. Level-shifter technique is used to lower the compliance range, but it requires additional circuitry to compensate the extra offset introduced in the current, thereby increases the circuit complexity and power requirement [1, 2]. The CMs based on FGMOS technique have the problems of charge trapping and poor bandwidth due to a lot of parasitic capacitances involved [3, 4]. Bulk-driven based CMs too suffer from poor bandwidth and reduced swing [5–7]. Koliopoulos et al. in [8] and Laoudias et al. in [9] have suggested CMs with low compliance voltage requirement. However, these CMs have the problem of accuracy in current matching. Conventionally transistors in cascode configuration are used to increase the output resistance and to improve the accuracy of a CM. However, cascoding the transistors increases the requirement of the supply voltage and also reduces the input/output compliance range, which makes it non-compatible with today’s technology trend. Here, a novel high performance cascode CM has been proposed. The wide swing characteristic of self-biased cascode CM is utilized and its bandwidth is enhanced using resistance compensation technique. Super-cascode configuration has been used at the output side of the CM, to 123 68 Analog Integr Circ Sig Process (2013) 75:67–74 improve the output impedance of the proposed circuit. Finally, active replacement of passive resistances used in the developed circuit has been carried out, so that it is compatible with presently used full monolithic integrated circuit technology. The paper is organized as follows: Selfbiased cascode CM is explained in Sect. 2. Application of resistive compensation technique to increase bandwidth is discussed in Sect. 3. In Sect. 4, implementation of supercascode technique for improving output impedance is shown. Active implementation of the resistances of the proposed CM is explained in Sect. 5. Section 6 deals with simulation results using Mentor Graphics Eldospice based on TSMC 0.18 lm CMOS technology, which is followed by conclusions drawn. iB iB iOUT iIN + M3 + M1 + vIN VON+VT vOUT M4 - + M2 VON+VT - - 2 Self-biased high swing cascode current mirror VSS To obtain high performance CM, a lot of work has been carried out in literature. Various CMs working in different regions of operation of MOSFET, namely saturation [8– 10], triode [11, 12] and subthreshold [13], have been reported time to time. The CMs using MOSFETs operating in saturation mode have higher transconductance (gm) than those based on MOSFETs operating in triode or subthreshold mode. This leads to higher bandwidth and better input and output impedances. For such CMs, all MOSFETs should satisfy the condition: VDS VGS VT ð3Þ Also, compliance voltage of the output terminals of this cascode CM is given as: Vout;min ¼ VT þ 2VON ð4Þ The self-biased high swing cascode current mirror (SBCCM) is shown in Fig. 2 [15]. In SBCCM, if the value 123 + iB + R vON iOUT - + M3 + vIN M4 - M2 vOUT VON+VT M1 + - - VON+VT VSS Fig. 2 Self-biased high swing cascode current mirror ð2Þ Then, the input compliance voltage of a cascode CM shown in Fig. 1 is given as [14]: Vin;min ¼ 2VT þ 2VON iB iIN ð1Þ where, Vxy represents the voltage drop across x and y terminals (through out this paper) and VT is the threshold voltage of the MOSFET. This shows that the input/output compliances of a CM depend on the minimum voltage drop required by the MOSFETs of the mirror to operate in saturation mode. High compliance range is useful for accurate operation of CM with low power supply voltages. The accuracy of low voltage analog circuits will be enhanced when designed using these CMs. Let, VDSðminÞ ¼ VGS VT ¼ VON ðsayÞ Fig. 1 Simple cascode current mirror of resistance R is chosen in such a way that the potential drop across it is ‘VON’, then in this circuit the values of input and output compliance voltages are ‘VT ? 2VON’ and ‘2VON’ respectively. This show an improvement by a factor of ‘VT’ as compared to cascode CM, which leads to lowering of supply voltage required by the CM for its proper operation. The SBCCM provides the advantage of high output resistance and high voltage swing along with low power consumption. The input and output impedances of SBCCM, shown in Fig (2), respectively are given as: Analog Integr Circ Sig Process (2013) 75:67–74 rin 1 þR gm4 69 ð5Þ rout ðr01 r02 gm2 Þ ð6Þ where, gmi is small signal transconductance of NMOS Mi and roi is small signal output resistance of NMOS Mi. Here i = 1, 2…,4. where Cgsi represent gate-source capacitance of NMOS Mi. Bandwidth of this second order low pass system is given as: rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi g g 0 m2 m4 x0 ¼ ð8Þ Cgs2 Cgs1 þ Cgs4 Let Cgs1 ¼ Cgs4 ¼ C1 and Cgs1 ¼ Cgs2 ¼ C2 rffiffiffiffiffiffiffiffiffiffiffiffiffiffi gm2 gm4 0 x0 ¼ 2C1 C2 3 Bandwidth extension of SBCCM Bandwidth is one of the most important features of any CM. It affects the overall speed of the device which incorporates the CM. In this section, resistive compensation method to increase the bandwidth of SBCCM without influencing its DC characteristics is presented [16, 17]. The resistance compensated circuit of SBCCM (proposed-I circuit) for achieving higher bandwidth is shown in Fig. 3. In this circuit, a compensating resistance ‘R’ is added between the gates of primary pair transistors M1 and M4, to enhance the bandwidth. The response of the CM gets delayed due to introduction of the compensating resistance. It introduces a zero in transfer function which cancels off the delay with proper choice of resistance value. The transfer function of non-compensated SBCCM shown in Fig. 2, neglecting input and output capacitors and conductances, is given as: gm2 gm4 ggm1 m4 Cgs2 ðCgs1 þCgs4 Þ 0 AI ðsÞ ¼ ð7Þ gm2 gm2 gm4 m1 þgm4 s2 þ s Cggs1 þ þ þCgs4 Cgs2 Cgs2 ðCgs1 þCgs4 Þ iB iIN ð9Þ ð10Þ Using similar assumptions as employed to derive (7), the small signal model for bandwidth calculation of SBCCM with resistance compensation is shown in Fig. 4. From the circuit it can be analyzed that: iout ðsÞ ¼ gm2 v15 ð11Þ v12 iin ðsÞ ¼ sCgs2 v15 þ sCgs3 v13 þ R v12 v24 ¼ sCgs1 v2 þ þ gm3 v13 R R1 v24 ¼ sCgs4 v4 R1 ð13Þ gm3 v13 ¼ gm4 v4 sCgs3 v13 ð15Þ gm2 v15 ¼ gm1 v2 sCgs2 v15 ð16Þ ð12Þ ð14Þ Combining and solving above equations we get: iout ðsÞ iin ðsÞ ¼ gm2 2 s Cgs1 Cgs4 R1 þ sCgs1 þ sCgs4 þ gm4 sCgs2 þ sR1Cgs4 þ 1 gm2 þ sCgs2 ð17Þ gm1 iB This can be simplified as: R iOUT 6 Cgs2 M3 M2 1 Cgs3 R gm3v13 gm2v15 5 iin 2 R1 3 R1 M1 M4 iout Cgs1 gm1v2 gm4v4 4 Cgs4 VSS Fig. 3 Resistance compensated SBCCM (proposed-I) Fig. 4 Small signal model for calculating bandwidth of resistance compensated SBCCM 123 70 Analog Integr Circ Sig Process (2013) 75:67–74 gm1 gm2 sCgs4 R1 þ 1 iout ðsÞ ¼ 3 2 iin ðsÞ s Cgs1 Cgs2 Cgs4 R1 þ s Cgs2 Cgs4 R1gm1 þ Cgs1 Cgs4 R1gm2 þ Cgs1 Cgs2 þ Cgs2 Cgs4 þs Cgs2 gm1 þ Cgs1 gm2 þ Cgs4 gm2 þ Cgs2 gm4 þ gm2 gm4 The mid-band gain, as obtained by substituting s = 0 in (18), is given as: iout gm1 ¼ iin gm4 ð19Þ This is same as that of un-compensated case as can be calculated using (7). Substituting (9) in (18) and simplifying, we get: ð18Þ obtained by using resistive compensation technique. This was obtained by initially transforming a 2-pole low pass system into a 3-pole and 1-zero low pass system by resistance compensation technique. Then, finally cancelling the introduced zero with the dominant pole which can be easily obtained by proper choice of the compensating resistance. 1 g g s þ m1 m2 C1 R1 iout ðsÞ ¼ gm1 gm2 2gm2 gm2 gm4 2 iin ðsÞ m4 3 2 C1 C2 s þ s C1 þ C2 þ C1 R1 þ s gm1C2þg þ þ 2 C1 C2 R1 R1 C C2 R1 1 1 This is a transfer function of third order low pass system with 1-zero and 3-poles. Now, if R1 ¼ 1 gm4 ð21Þ Then, (20) can be factorized as: iout ðsÞ gm1 gm2 ¼ g iin ðsÞ m1 C1 C2 s2 þ s þ gm2 þ C1 C2 1 C1 R1 þ C1gCm22 R1 C1 C2 In proposed-I circuit shown in Fig. 3, the bandwidth has been improved a lot. Also being a circuit of cascode configuration, its output resistance is high. But it can be iB iB ð23Þ iB1 iIN R iOUT M6 M2 M3 M5 C1 C2 This is a transfer function of a second order low pass system. From (23) the bandwidth of resistance compensated SBCCM can be given as: rffiffiffiffiffiffiffiffiffiffiffiffiffiffi gm2 gm4 x0 ¼ ð24Þ C1 C2 Comparison of (10) and (24), shows that an improvement by a factor of H2 in bandwidth has been 123 4 Implemetion of super-cascode configuration on proposed-I circuit to achieve high output impedance ð22Þ On choosing R1 = 1/gm4, the zero introduced due to resistance compensation gets cancelled with the dominant pole, thereby reducing the transfer function to a second order low pass system. Relation (21) can be used to modify (22) as: iout ðsÞ gm1 gm2 ¼ gm1 C2 þgm2 C1 þgm4 C2 iin ðsÞ 2 C1 C2 s þ s þ gm2 gm4 ð20Þ R1 M4 M1 VSS Fig. 5 Resistance compensated SBCCM with high output resistance (proposed-II) Analog Integr Circ Sig Process (2013) 75:67–74 71 iout 1 3 iB 4 iB iB2 iB1 r04 r06 gm4(-v2) gm5v32 iIN r05 gm6v1 iOUT M6 M10 + 2 2 vout - M5 M3 M2 M9 M1 M8 r02 M7 M4 Fig. 6 Small signal model for calculating output resistance of proposed-II circuit VSS Fig. 7 Final proposed high-performance self-biased cascode current mirror (proposed-III) improved further by using super cascode configuration [18, 19] at the output side. The introduced output stage uses MOSFETs M5, M6 and current source iB1, as shown in Fig. 5. The supply voltage requirement of this circuit is same as that of proposed-I circuit. The small signal model for calculating output resistance of this proposed-II circuit is shown in Fig. 6. vout rout ¼ ð25Þ iout From Fig. 6 iout ¼ gm5 v32 þ vout v2 r05 ð26Þ v2 ¼ iout r02 ð27Þ v3 ¼ r06 gm6 v1 ð28Þ v2 v1 ¼ r04 gm4 v2 ð29Þ Simplifying (26)–(29), we get: 1 vout iout 1 þ gm5 r06 gm6 ð1 þ gm4 r04 Þ þ gm5 þ r02 ¼ r05 r05 5 Final proposed high performance CM circuit with passive resistors replaced by active ones In full monolithic integrated circuits, passive resistances are made of poly-silicon. They consume a large amount of chip area and have rather higher tolerances. Thus, their utilization in any integrated circuit is not appreciable. At the same time, tracking of the MOS transconductance, which is highly dependent on process parameters and temperature, by passive resistance is quite difficult. Figure 7 shows the final proposed circuit, which has been obtained by the active implementation of all the passive resistances appearing in the proposed circuit of Fig. 5. In this final proposed circuit, resistor R1 has been realized using a MOSFET M7 in triode region and MOSFETs M8 and M9 in saturation region [20]. The channel resistance of M7 needs to match 1/gm4 for optimum bandwidth. The channel resistance of M7 operating in triode region can be given as [14]: r07 ¼ ð30Þ Now, since gm r 0 1 Thus (30) can be written in simplified form as: vout gm4 r04 gm5 r05 gm6 r06 r02 rout ¼ iout ð31Þ ð32Þ From (32), it can be seen that by using super-cascode structure, the output resistance of the proposed-II circuit becomes very high (theoretically in GX range). However in actual practice it is limited due to drain-substrate leakage currents at the drain of MOSFET M5. ln Cox WL 1 Vgs7 VT ð33Þ where all symbols have their standard meaning. Also, resistor R used in the proposed-II circuit of Fig. 5 has been realized using MOSFET M10 as MOS diode, in Fig. 7. The small signal resistance of such a MOS diode is given as [12]: r10 1 gm10 ð34Þ Equations (33) and (34) indicate that the active resistances shown in the proposed-III circuit are dependent on the aspect ratios of the MOSFETs M7 and M10. Thus, the desired voltage drop required in the circuit 123 72 Analog Integr Circ Sig Process (2013) 75:67–74 Fig. 8 Output versus input current transfer characteristics curve of the circuits Fig. 9 Curve showing current transfer accuracy of the circuits Fig. 10 Frequency response representing bandwidth of the circuits and cancellation of dominant pole can be achieved by varying the aspect ratios of these MOSFETs. The circuit shown in Fig. 7 is the final proposed circuit of the improved high performance CM. This proposed low voltage CM has higher bandwidth, a very high output 123 resistance and improved current matching characteristics. In this proposed circuit, the passive resistances have been replaced by active ones and for a wide range of operation, its output current is shown to be matched with input current with very high degree of accuracy. Analog Integr Circ Sig Process (2013) 75:67–74 73 Table 1 Comparative results Performance factor SBCCM [10] Proposed-I Proposed-II Proposed-III (final) Range (lA) 0–500 \10 0–500 0–500 0–500 rin (X) 925 100 789 661 679 rout (MX) 0.879 200 0.768 326 482 BW (GHz) 1.68 0.04 2.469 NA 2.262 Supply voltage (V) -1 1.2 -1 -1 -1 6 Simulation results In this section, Eldospice simulation results for proposed and other circuits have been presented. All of the simulations are carried on Mentor Graphics Eldospice based on TSMC 0.18 lm CMOS technology, using a single supply voltage of -1 V. For all the proposed circuits, aspect ratios of the transistors (if used) are M6 = 0.18/0.18, M7 and M10 = 10/ 0.18 and for rest of the MOSFETs aspect ratio is equal to 1/0.18. For all the DC analysis, iIN is varied from 0 to 500 lA. Figure 8, shows the output vs. input current characteristics of SBCCM and all the proposed circuits. As shown in this figure the proposed circuits exhibit great degree of accuracy for a wide range of operation, making them suitable for very low voltage applications. Also the current transfer characteristics accuracy in percentage is shown in Fig. 9. This figure reveals the fact, that final proposed circuit has very low current transfer error (less than 0.5 %) for the maximum range of operation. Furthermore, it reflects that the maximum error in current transfer is limited to 2 %, that too for very low current values. The frequency response of the conventional and proposed CMs is shown in Fig. 10. As reflected in this figure, the bandwidth of the final proposed CM is 2.26 GHz. The simulated values of rin and rout of the final proposed high performance CM are 679 X and 482 MX respectively. These values along with the corresponding values of other circuits of this paper are tabulated in Table 1. Besides, simulated results are compared with [10] to prove the robustness of the proposed CM. These comparative results are summarized in Table 1. These results illustrate the fact that bandwidth has improved considerably thereby increasing the working speed of the IC. Furthermore, the proposed circuit is able to operate over a wider range (0–500 lA) in comparison to [10]. Operation of the proposed circuit, with such a low voltage for a broad current range and higher bandwidth along with its simple structure can be considered as a significant achievement. 7 Conclusions A novel self-biased cascode CM with very high performance characteristics has been introduced and verified with the help of simulations. Bandwidth enhancement by a compensation resistor between the gates of the primary transistor pair of CM is shown. Improvement in output resistance has been carried out by implementation of supercascode configuration at the output side. The active realization of the resistances, to overcome the drawbacks of passive components has also been discussed. The proposed saturation region CM, where all required resistances have been replaced by active components, shows high degree of accuracy over a wide input current range. Small signal analysis has been carried out at each step and the results have been validated using Mentor Graphics Eldospice based on TSMC 0.18 lm CMOS technology using -1 V supply voltage. References 1. Ramirez-Angulo, J. (1994). Current mirrors with low input and low output voltage requirements. In Proceedings of the 37th Midwest Symposium on Circuits and Systems (Vol. 1, pp. 107–110). Lafayette: Lafayette Hilton and Towers. 2. Rajput, S. S., & Jamuar, S. S. (2000). A high performance current mirror for low voltage designs. In The 2000 IEEE Asia–Pacific conference on circuits and systems (IEEE APCCAS) (pp. 170–173). Tianjin: IEEE. 3. Sharma, S., Rajput, S. S., Magotra, L. K., & Jamuar, S. S. (2002). FGMOS based wide range low voltage current mirror and its applications. In Asia–Pacific conference on circuits and systems (APCCAS ‘02) (Vol. 2, pp. 331–334). Singapore: IEEE. 4. Aggarwal, B., & Gupta, M. (2009). Low-voltage cascode current mirror based on bulk-driven MOSFET and FGMOS techniques. In International conference on advances in recent technologies in communication and computing (ARTCom ‘09) (pp. 473–477). IEEE: Kottayam. 5. Yani, L., Yintang, Y., & Zhangming, Z. (2010). A novel lowvoltage low-power bulk-driven cascade current mirror’. In Third international conference on advanced computer theory and engineering (ICACTE) (Vol. 3, pp. V3-78–V3-83). Chengdu: ICACTE. 6. Blalock, B. J., & Allen, P. E. (1995). A low-voltage, bulk-driven MOSFET current mirror for CMOS technology. In IEEE international symposium on circuits and systems (ISCAS ‘95), 1972–1975. Seattle: IEEE. 7. Lakkamraju, N., & Mal, A. K. (2011). A low voltage high output impedance bulk driven regulated cascode current mirror. In Third international conference on electronics computer technology (ICECT) (Vol. 3, pp. 79–83). Kanyakumari: ICECT. 8. Koliopoulos, C., & Psychalinos, C. (2007). A comparative study of the performance of the flipped voltage follower based low- 123 74 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Analog Integr Circ Sig Process (2013) 75:67–74 voltage current mirrors. International Symposium on Signals, Circuits and Systems (ISSCS), 1, 1–4. Laoudias, C., & Psychalinos, C. (2008). Low-voltage CMOS current-mode filters using current mirrors: Two alternative approaches. In The 14th IEEE mediterranean electrotechnical conference (MELECON) (pp. 435–440). Ajaccio : MELECON. Ramirez-Angulo, J., Carvajal, R. G., & Torralba, A. (2004). Low supply voltage high-performance CMOS current mirror with low input and output voltage requirements’. IEEE Transactions on Circuits and Systems II: Express Briefs, 51(3), 124–129. Prodanov, V. I., & Green, M. M. (1996). CMOS current mirrors with reduced input and output voltage requirements. Electronics Letters, 32(2), 104–105. Mulder, J., Van der Woerd, A. C., Serdijn, W. A., & Van Roermund, A. H. M. (1996). High-swing cascode MOS current mirror. Electronics Letters, 32(14), 1251–1252. Tanno, K., Ishizuka, O., & Tang, Z. (1996). Low voltage and low frequency current mirror using a two-MOS subthreshold op amp. Electronics Letters, 32(7), 605–606. Allen, P. E., & Holberg, D. R. (2004). CMOS analog circuit design (2nd ed.). New York: Oxford University Press. Brooks, T. L., & Rybicki, M. A. (1994). Self-biased cascode current mirror having high voltage swing and low power consumption. U.S. patent no. 5359296, 25 Oct 1994. Voo, T., & Toumazou, C. (1995). High-speed current mirror resistive compensation technique. Electronics Letters, 31(4), 248–250. Gupta, M., Aggarwal, P., Singh, P., & Jindal, N. K. (2009). Low voltage current mirrors with enhanced bandwidth. Analog Integrated Circuits and Signal Processing, 59(1), 97–103. Torralba, A., Carvajal, R. G., Ramirez-Angulo, J., & Munoz, E. (2002). Output stage for low supply voltage, high-performance CMOS current mirrors. Electronics Letters, 38(24), 1528–1529. Torralba, A., Carvajal, R. G., Munoz, F., & Ramirez-Angulo, J. (2003). New output stage for low supply voltage, high-performance CMOS current mirrors. In Proceedings of the 2003 International Symposium on Circuits and Systems (ISCAS ‘03) (Vol. 1, pp. I-269–I-272). Taipei: ISCAS. Voo, T., & Toumazou, C. (1996). Precision temperature stabilised tunable CMOS current-mirror for filter applications. Electronics Letters, 32(2), 105–106. Maneesha Gupta received her B.E. and M.E. in Electronics & Communication Engineering from Government Engineering College, Jabalpur in the years 1981 and 1983, respectively. She received her PhD. in Electronics Engg. from Indian Institute of Technology (IIT), Delhi in 1990. Dr. Gupta served as lecturer in various esteemed institutes of India, for the period 1981-1998. Since 1998, she is with Netaji Subhas Institute of Technology, New Delhi and is presently serving as Professor in, Electronics and Communication 123 Engineering Department in the same institute. Her teaching and research interests are Switched Capacitors Circuits and Analog Signal processing. Bhawna Aggarwal was born in 1980. She received her B.E. in Electronics & Communication Engineering from Indira Gandhi Institute of Technology, Delhi in 2002, M.E. in Electronics & Communication Engineering from Delhi College of Engineering, New Delhi in 2006 and is currently involved in PhD. work, in NIT Kurukshetra. Her area of research is low power design techniques. She is currently working as Assistant Professor in Maharaja Agrasen Institute of Technology, Sec 22, Rohini, New Delhi-110086. Anil Kumar Gupta received B.Tech. (ECE) from G.B.Pant University of Agriculture and Tecnology in 1972. He received M.Tech. and Ph.D. in Electrical Engineering from Indian Institute of Technology, Kanpur in the years 1974 and 1985 respectively. He served as Assistant Station Engineer in All India Radio during the period 1974-78. Since 1985, he is with National Institute of Technology, Kurukshetra where he is presently serving as Professor, Electronics and Communication Engineering for the last thirteen years. His areas of interest are Semiconductor devices and Technology, Embedded systems, Instrumentation and VLSI Design.