Supplementary First-Order All-Pass Filters with Two Grounded Passive Elements Using FDCCII

Transcription

1 DIOENGINEERING, VOL. 2, NO. 2, JUNE Supplementary First-Order All-Pass Filters with Two Grounded Passive Elements Using Bilgin METIN, Norbert HERENCSAR 2, Kirat PAL 3 Dept. of Management Information Systems, Bogazici University, Hisar Campus, Bebek-Istanbul, Turkey 2 Dept. of Telecommunications, Brno University of Technology, Purkynova 8, 62 Brno, Czech Republic 3 Dept. of Earthquake Engineering, Indian Institute of Technology, Roorkee, , Uttaranchal, India DIOENGINEERING, VOL. 8, NO., APRIL 29 bilgin.metin@boun.edu.tr, herencsn@feec.vutbr.cz, kiratfeq@iitr.ernet.in Supplementary First-Order All-Pass Filters with Two Abstract. In this study, two novel first-order all-pass filters are proposed using only one Grounded grounded resistorpassive and one Elements VM circuits in [], Using [6] use two differential difference cur- resistors, two capacitors and two current conveyors. The grounded capacitor along with a fully differential current rent conveyors (DDCC) [2] and three grounded passive elements HERENCSAR and they 2 are, Kirat cascadable. PAL 3 The circuit in [7] employs conveyor (). There is no element-matching Bilgin METIN restriction. The presented all-pass filter circuits can be made elec- differential voltage conveyor (DVCC) [22] and two resistors., Norbert Dept. of Management Information Systems, Bogazici University, Hisar Campus, Bebek-Istanbul, Turkey tronically tunable due to 2 the electronic resistors. Furthermore, the presented circuits3 Dept. enjoyof high-input Earthquake Engineering, impedanceindian for Institute ing block of Technology, (ABB) Roorkee, called voltage , Uttaranchal, differencing India differential in- In [8], applications of the recently introduced analog build- Dept. of Telecommunications, Brno University of Technology, Purkynova 8, 62 Brno, Czech Republic easy cascadability. The theoretical results are verified with put buffered amplifier (VD-DIBA) is presented. The proposed VM all-pass kiratfeq@iitr.ernet.in filter is composed of single VD-DIBA SPICE simulations. dr.bilgin.metin@gmail.com, herencsn@feec.vutbr.cz, and one grounded capacitor. The circuits in [9] have a single fully they differential are cascadable. current The conveyor circuit () in [4] employs [23] as ac- Abstract. In this study, two novel first-order all-pass filters are proposed using only one grounded resistor and tive elements differential andvoltage two passive conveyor components. (DVCC) [8] and two Keywords one grounded capacitor along with a fully differential resistors. The circuits in [] have a single fully differential current conveyor (). There is not element-matching In current this study, conveyor in addition () to [9] theas active elements based canonical and restriction. The presented all-pass filter circuits can Analog filter, all-pass filter, cascadable filter, high-q and be cascadable two passive circuits components. of [9] in the literature, two supplementary cascadable In this study, VMin first-order addition to all-pass the filters based are pre- made electronically tunable due to the electronic resistors. band-pass filter, grounded capacitor,, MOS- Furthermore, the presented circuits enjoy high-input FET based resistors. sented. canonical The proposed and cascadable cascadable circuits of circuits [] in employ the literature, impedance for easy cascadability. The theoretical results only one two supplementary cascadable VM first-order all-pass are verified with SPICE simulations. grounded resistor and one capacitor and they have no element matching employ only restriction one grounded compared resistor and to [4] [6]. one capacitor The and intro- filters are presented. The proposed cascadable circuits ducedthey circuits have consist no element of one matching fewer restriction active element compared in to comparison []-[3]. to [7]. The Moreover, introduced circuits as an application consist of one example fewer the. Introduction Keywords active element in comparison to [4]. Moreover, as an proposed all-pass filters are used in the implementation of In the literature different Analog filter, active all-pass elements filter, [] cascadable have been filter, high-q application example the proposed all-pass filters are used band-pass filter, grounded capacitor,, the high in the quality implementation factor (high-q) of the high band-pass quality factor (BP) (high-q) filter circuit [24] [28] band-pass that (BP) is used filter frequently circuit [2]-[24] in thethat intermediate is used fre- used in the design of MOSFET voltage-mode based resistors. (VM) all-pass filters [2] [9] for different useful features, such as high input frequently in the intermediate frequency stages of the quency stages of the receiver circuits [27]. Different from the impedance, reduced number of active and passive elements receiver circuits [23]. Different from the circuits in [2]- circuits in [24] [28], the presented high-q band-pass filter or having grounded. capacitors, Introduction [24], the presented high-q band-pass filter example has a etc. Some recent VM filter example fine-tuning has a fine-tuning capability for its capability pole frequency for its and pole it consists frequency structures [3] [9] emphasize In the literature the importance different active of the elements design[] have and it of consists only grounded of onlycapacitors. groundedthe capacitors. simulation The results simulation are with only groundedbeen passive used elements in the design forof easy voltage-mode integrated(vm) circuit (IC) implementation. filters [2]-[] Grounded for different IC capacitors use full features, have less such as high all-pass used to verify the operation of the circuits. results are used to verify the operation of the circuits. input impedance, reduced number of elements or having parasitics comparedgrounded to floating capacitors counterparts. etc. Some recent Furthermore, VM filter circuits the floating capacitors []-[] require emphasize an ICthe process importance with of the twodesign poly 2. and Circuit Description with only layers. On the other grounded hand, the passive grounded elements resistors for easy integrated can be replaced by MOS based electronic resistors [2] providing the eight-terminal analog building block shown symbolically circuit (IC) 2. Fully differential and current Circuit conveyor Description () is an implementation. Grounded IC capacitors have less parasitics compared to floating counterparts. Furthermore, Fully in Fig. differential. Considering current the non-idealities conveyor caused () by the is an advantages of less the chip floating areacapacitors and tunability. require an The IC process electronically tunable circuits layers. have On been the other an important hand, the grounded researchresistors area can be with two poly eight-terminal ABB shown symbolically in Fig.. Considein the design of analog replaced integrated by MOS circuits, based electronic because resistors the tolerances of the electronic components in the IC realization can [6] providing V the advantages of less chip area and tunability. The I V electronically tunable circuits have been an important be very high and thus research fine-tuning area the is necessary. V design of analog integrated circuits, IZbecause the tolerances of the electronic components in the V X- In [3], the IC VM realization all-pass can section be very high is designed and thus fine-tuning by is means of an operational necessary. transconductance amplifier (OTA), unity-gain differential amplifier, The VM circuits activein voltage [] employ divider, two resistors, and I IXtwo grounded capacitor. capacitors The VM and two circuits current in conveyors. [4] employ The VM twocircuits in Fig.. Fig. The. symbol The symbol of the of the. [2], [3] use two differential difference current conveyors (DDCC) [7] and three grounded passive elements and

2 434 B. METIN, N. HERENCSAR, K. PAL, SUPPLEMENTARY FIRST-ORDER ALL-PASS FILTERS WITH TWO GROUNDED... X- ZX- Z 2 ZX- Z 2 Z Z 2 X- X- R C R C R C X- X- C R C R C (c) R Fig. 2. Presented general structure of VM all-pass filter, first presented VM all-pass filter circuit, (c) second presented VM all-pass filter circuit. ring the non-idealities caused by the physical implementation of the [23], it is described with a matrix equation as follows: V V X I I Z = β β 2 β 3 β β 2 β 4 α P α N I I X V V V V where ideally β = β 2 = β 3 = β 4 = and α P = α N = that represent the voltage and current transfer ratios of the FD- CCII, respectively. The transfer function of an all-pass filter can be given as follows: (s) (s) = K sτ (2) + sτ where K is the gain constant and its sign determines whether phase shifting is from to π or from π to, and τ is the time constant. The proposed circuits are shown in Fig. 2. The general VM transfer function of the circuit in Fig. 2 is given for the ideal case (β = β 2 = β 3 = β 4 = and α P = α N = ): () = Z Z 2 Z + Z 2. (3) Transfer function in (3) yields to two all-pass filter circuits under the specialization of Z and Z 2 shown in Fig. 2 and 2(c). Their transfer function can be given as follows: + scr = K + scr where K = + for Z = R and Z 2 = /sc illustrated in Fig. 2 and where K = for Z = /sc and Z 2 = R illustrated in Fig. 2(c). Considering the active element nonidealities as given in (), the transfer function for the circuit in Fig. 2(c) can be given as follows: (4) = α Nβ 4 + α P β 3 scr. () (α N + α P scr)β 2 The parasitic capacitances in the implementation of the active elements limit the high frequency operation. To evaluate high frequency performance, the frequency dependency of the current and voltage transfer ratios should be taken into account. Therefore, α(s) and β(s) for will be modeled with first-order functions for simplicity as: α N (s) = α N + sτ N, α P (s) = α P + sτ P, β k (s) = β k + sτ βk, for k =,2,3,4 and where the α N, α P, and β k are the value of the current and voltage transfer ratios at low frequencies and ω N = /τ N, ω P = /τ P, and ω β = /τ β represent their corresponding poles. Combining () and (6), the frequency dependent transfer function of the presented allpass circuit in Fig. 2(c) can be obtained as follows: ( ) [ α + N β 4 ( + sτ P ) ( ) ] + sτ β3 + sτβ2 = β 2 [ +α P β 3 scr( + sτ N ) ( ) + sτ ] β4 ( ). + sτβ3)( + sτβ4 α N ( + sτ P )+ +α P scr( + sτ N ) Equation (7) shows that extra poles appear due to onepole model additional to pole at /CR. If the frequency of these additional poles are sufficiently higher than the pole of the presented all-pass filter such as (CR) min{ω β3, ω β4, ω αp, ω αn }, their effect on the frequency can be ignored. 3. Simulation Results To verify theoretical results the proposed filter circuit shown in Fig. 2(c) is simulated by the SPICE simulation program. The was realized based on the CMOS implementation in [23] (Fig. 3) and simulated using.3 µm, level 3 MOSFET parameters. The aspect ratios of the MOS transistors are given in Tab.. DC supply voltages of ±.3 V and V bp, V bn biasing voltages of V are used. Biasing currents are chosen as µa. The frequency response of the proposed circuit in Fig. 2(c) is given in Fig. 4 for (6) (7)

3 DIOENGINEERING, VOL. 2, NO. 2, JUNE 2 43 VDD M3 M4 M8 2 M7 M8 M9 7 9 M33 M37 M4 M M9 Vbp Vbp M3 M34 M38 M42 IB M3 M4 M M M6 X- 6 4 M6 M7 Vbn 3 M M Vbn 8 M3 M32 M3 M36 M43 M44 M39 M4 ISB VSS Fig. 3. CMOS implementation based on [23]. C = pf and R =. kω. The effects of the temperature on frequency response are examined for C, 27 C, and C in Fig. 4. The frequency response is slightly affected by the temperature. Time domain analysis of the proposed circuit in Fig. 2(c) for a.4 V peak-to-peak input signal at khz is given in Fig. for passive element values of C = pf and R = kω. Total harmonic distortion at this frequency is found as. %. There is a 2 mffset voltage at the output caused by the non-idealities of the. The presented all-pass filter is used to implement an electronically tunable high-q band-pass (BP) filter application [24] [28] as shown in Fig. 6. The quality factor of the band-pass filter is determined by R A and R B that is approximately equal to Q R A /R B [27]. In Fig. 6, the capacitor and resistor values are chosen as C = C 2 = 3 pf, R = R 2 = 2 kω, R A = 3 kω, and R B = kω for a pole frequency of 2.6 MHz. Although the theoretical Q value is 3, in the simulations we have obtained Q = 2. The simulation results are given in Fig. 7. The center frequency of the BP filter circuit is found as 2.2 MHz in the simulation. Deviations from the ideal response result are caused by the nonidealities of the used in the simulations. Fortunately, this deviation in the pole frequency can be corrected by fine tuning that can be achieved replacing grounded resistors with MOSFET based resistors [2] as shown in Fig. 6. The simulation results for the fine tuning of this circuit are illustrated in Fig. 8. The transistor aspect ratios for the MOS- FET based electronic resistor in Fig. 6 are chosen as (W/L) M = (W/L) =. µm/.4 µm and capacitor values are chosen as C = C 2 = 3 pf. The pole frequency of the circuit is tuned between 3.4 MHz and 4.7 MHz by changing the control voltage V C is changed between.8 V and. V. The parasitics and the non-idealities of the active elements cause change in the magnitude of the gains at the center frequency of the filter at high frequencies. Transistors W(µm) L(µm) M-M M7-M9, M3-M, M8, M9, 2, 3,, 7, 9, M3, M33, M34, M37, M38, M4, M M-, M6, M7,,, 4, 6, 8, M3, M32, M3, M36, M39, M4, M43, M Tab.. Transistor aspect ratios. -d -d -d -2d -2d - -2d - Hz -2d.kHz khz khz.mhz MHz MHz _ Hz.kHz khz khz.mhz MHz MHz Simulated.. Ideal _ Simulated.. Ideal - - -d -d -d -d -d -2d -2d -2d -2d Hz.kHz khz Hz.kHz khz khz.mhz khz.mhz MHz MHz MHz MHz _ Simulated _. Simulated. Ideal Ideal Fig. 4. response of the presented circuit, the Figure Figure effectresponse of the of temperature of the the presented change circuit. on the The The frequency effect of of the response. the temperature change change on the on the frequency response

4 436 B. METIN, N. HERENCSAR, K. PAL, SUPPLEMENTARY FIRST-ORDER ALL-PASS FILTERS WITH TWO GROUNDED... 3mV 2mV Amplitude mV -3mV 9us us 2us 4us 6us 8us 2us 22us 24us Input Ideal Output.. Simulated Output Time Figure. Time domain analysis of the presented circuit Fig.. Time domain analysis of the presented circuit khz Simulated.MHz 3.MHz MHz Ideal Figure 7. response of the high-q band-pass filter example Fig. 7. response of the high-q band-pass filter example. C R 2 R2 [db] X- C M C M VC 2 2 X- Rmos2 M Rmos M Rmos2 Rmos +VC Figure 6. A high-q band-pass filter example using presented all-pass filter Electronically tunable form of the example band-pass filter Fig. 6. A high-q band-pass filter example using presented all-pass filter, electronically tunable form of the example band-pass filter. 4. Conclusion In this study, two minimal first order all-pass filter realizations are given using only grounded passive elements. The proposed circuits have the advantage of having high input impedance for easy cascadability. The presented all-pass filter circuits are used in a tunable high-q band-pass filter example. Simulations are performed to verify the theory. Acknowledgements This work was supported by Bogazici University Research Fund with the project code 8N34, Czech Ministry of Education under research program MSM 2633, and GACR projects under No. P2//P489 and P2/9/68. Authors also wish to thank the reviewers for their useful and constructive comments KHz.MHz 3.MHz MHz 3MHz Vc=.V Vc=.9V Vc=.8V kHz.MHz 3.MHz MHz 3MHz Vc =.8V Vc =.9V Vc =.V Figure 8. Illustrating fine-tuning of the pole-frequency for the high-q band-pass filter example Figure 8. Illustrating fine-tuning of the pole-frequency for the high-q band-pass filter example Fig. 8. Illustrating fine-tuning of the pole-frequency for the high-q band-pass filter example. References [] BIOLEK, D., SENANI, R., BIOLKOVA, V., KOLKA, Z. Active elements for analog signal processing: classification, review, and new proposals. Radioengineering, 28, vol. 7, no. 4, p [2] KHAN, A., MAHESHWARI, S. Simple first order all-pass section using a single CCII. International Journal of Electronics, 2, vol. 87, no. 3, p [3] CAM, U., CICEKOGLU, O., GULSOY, M., KUNTMAN, H. New voltage and current mode first-order all-pass filters using single FTFN. Frequenz, 2, vol. 4, no. 7-8, p [4] TOKER, A., OZCAN, S., KUNTMAN, H., CICEKOGLU, O. Supplementary all-pass sections with reduced number of passive elements using a single current conveyor. International Journal of Electronics, 2, vol. 88, no. 9, p [] PANDEY, N., PAUL, S. K. All-pass filters based on CCII- and CCCII-. International Journal of Electronics, 24, vol. 9, no. 8, p [6] METIN, B., CICEKOGLU, O. Component reduced all-pass filter with a grounded capacitor and high impedance input. International Journal of Electronics, 29, vol. 96, no., p [7] HIGASHIMU, M., FUKUI, Y. Realization of all-pass networks using a current conveyor. International Journal of Electronics, 988, vol. 6, no. 2, p

5 DIOENGINEERING, VOL. 2, NO. 2, JUNE [8] BIOLEK, D., BIOLKOVA, V. All-pass filters employing differential OpAmps. Electronics World, 2, vol. 6, no. 89, p [9] METIN, B., PAL, K. Cascadable allpass filter with a single DO-CCII and a grounded capacitor. Analog Integrated Circuits and Signal Processing, 29, vol. 6, no. 3, p [] HERENCSAR, N., KOTON, J., JEBEK, J., VA, K., CI- CEKOGLU, O. ltage-mode all-pass filters using universal voltage conveyor and MOSFET-based electronic resistors. Radioengineering, 2, vol. 2, no., p [] KESKIN, A. U., AYDIN, C., HANCIOLU, E., ACAR, C. Quadrature oscillator using current differencing buffered amplifiers (CDBA). Frequenz, 26, vol. 6, no. 3-4, p [2] KUMAR, P., KESKIN, A. U., PAL, K. Wide-band resistorless allpass sections with single element tuning. International Journal of Electronics, 27, vol. 94, no. 6, p [3] KESKIN, A. U., PAL, K., HANCIOGLU, E. Resistorless first order all-pass filter with electronic tuning. International Journal of Electronics and Communications (AEU), 28, vol. 62, no. 4, p [4] HORNG, J. W. Current conveyors based allpass filters and quadrature oscillators employing grounded capacitors and resistors. Computers and Electrical Engineering, 2, vol. 3, no., p [] MAHESHWARI, S. High input impedance VM-APSs with grounded passive elements. IET Circuits Devices & Systems, 27, vol., no., p [6] MAHESHWARI, S. High input impedance voltage-mode first-order all-pass sections. International Journal of Circuit Theory and Applications, 28, vol. 36, no. 4, p [7] YUCE, E., MINAEI, S. Novel voltage-mode all-pass filter based on using DVCCs. Circuits, Systems and Signal Processing, 2, vol. 29, no. 3, p [8] BIOLEK, D., BIOLKOVA, V. First-order voltage-mode all-pass filter employing one active element and one grounded capacitor. Analog Integrated Circuits and Signal Processing, 2, vol. 6, no., p [9] MAHESHWARI, S., MOHAN, J., CHAUHAN, D. S. ltage-mode cascadable all-pass sections with two grounded passive components and one active element. IET Circuits Devices & Systems, 2, vol. 4, no. 2, p [2] WANG, Z. 2-MOSFET transistors with extremely low distortion for output reaching supply voltage. Electronics Letters, 99, vol. 26, no. 3, p [2] CHIU, W., LIU, S. I., TSAO, H. W., CHEN, J. J. CMOS differential difference current conveyors and their applications. IEE Proceedings - Circuits, Devices and Systems, 996, vol. 43, no. 2, p [22] ELWAN, H. O., SOLIMAN, A. M. Novel CMOS differential voltage current conveyor and its applications. IEE Proceedings - Circuits, Devices and Systems, 997, vol. 44, no. 3, p [23] EL-ADAWAY, A. A., SOLIMAN, A. M., ELWAN, H. O. A novel fully differential current conveyor and applications for analog VLSI. IEEE Transactions on Circuits and Systems Part II, 2, vol. 47, no. 4, p [24] COMER, D. J., MCDERMID, J. E. Inductorless bandpass characteristics using all-pass networks. IEEE Transactions on Circuits Theory, 968, vol., no. 4, p [2] TARMY, R., GHAUSI, M. S. Very high-q insensitive active RC networks. IEEE Transactions on Circuits Theory, 97, vol. 7, no. 3, p [26] MOSCHYTZ, G. S. High-Q factor insensitive active RC network, similar to the Tarmy-Ghausi circuit but using single-ended operational amplifiers. Electronic Letters, 972, vol. 8, no. 8, p [27] COMER, D. J. High-frequency narrow-band active filters. IEEE Transactions on Circuits Theory, 986, vol. 33, no. 8, p [28] METIN, B., CICEKOGLU, O. Tarmy-Ghausi (TG) circuit suitable for higher frequency of operation. Frequenz, 23, vol. 7, no. 7-8, p About Authors... Bilgin METIN received the B.Sc. degree in Electronics and Communication Engineering from Istanbul Technical University, Istanbul, Turkey in 996 and the M.Sc. and Ph.D. degrees in Electrical and Electronics Engineering from Bogazici University, Istanbul, Turkey in 2 and 27, respectively. He is currently an Assistant Professor in the Management Information Systems Department, Bogazici University. His research interests include continuous time filters, analog signal processing applications, current-mode circuits, computer networks, and network security. He was given the best student paper award of ELECO 22 conference in Turkey. Dr. Metin has over 3 publications in scientific journals or conference proceedings. Norbert HERENCSAR received the M.Sc. and Ph.D. degrees in Electronics & Communication and Teleinformatics from Brno University of Technology, Czech Republic, in 26 and 2, respectively. Currently, he is an Assistant Professor at the Dept. of Telecommunications, Brno University of Technology, Brno, Czech Republic. From September 29 through February 2 he was an Erasmus Exchange Student with the Dept. of Electrical and Electronic Engineering, Bogazici University, Istanbul, Turkey. His research interests include analog filters, current-mode circuits, tunable frequency filter design methods, and oscillators. He is an author or co-author of about 67 research articles published in international journals or conference proceedings. Since 28, Dr. Herencsar serves in the organizing and technical committee of the Int. Conf. on Telecommunications and Signal Processing (TSP). In 2 and 22, he is guest coeditor of TSP 2 and TSP 2 Special Issues on Signal Processing, published in the Radioengineering journal. Dr. Herencsar is Senior Member of the IACSIT and Member of the IAENG and ACEEE. Kirat PAL was born in Aligarh, India on 2th August 9. He received the B.Sc & M.Sc degree from the Aligarh Muslim University in 972 and 977 respectively and the Ph.D. degree from the University of Roorkee (Presently Indian Institute of Technology, Roorkee) in 982. He joined University of Roorkee as a scientific officer in 979 and worked in various capacities as lecturer, reader and at present holds the post of Associate Professor in Earthquake Engineering Dept. of Indian Institute of Technology Roorkee. His main research interests are analog circuits and signal processing, transducers, seismological instrumentation and digital image processing. Dr. Pal has authored more than research papers in the above areas in national, international journals and conferences.