-C Band-Pass Filter Using Improved Floating Current Source. -C pasovno prehoden filter četrtega reda z uporabo izboljšanega plavajočega tokovnega vira

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1 Original cientific paper Journal of Microelectronic, Electronic Component and Material Vol. 44, No. (04), 37 4 A 4 th Order Differential -C Band-Pa Filter Uing Improved Floating Current Source Firat Kaçar, Aren A.M. Shakir, Yain Özçelep Dept. of Electrical and Electronic Engineering, Univerity of Itanbul, Itanbul, Turkey Dept. of Mechanical Engineering, Kirkuk Univerity, Kirkuk, Iraq Abtract: Gm-C filter are the mot popular technique ued in implementing integrated continuou-time filter. In the tudy, we propoed a 4th order differential Gm-C band-pa filter uing improved floating current ource. The improved current ource tructure i imple and include fewer tranitor. Thi provide an effective ue of the chip area and bring implicity to the deign of circuit. Thu it reduce the invetment cot. The propoed filter tructure doe not contain the reitor which i very important for integration. All capacitor in propoed filter are grounded which reduce the paraitic effect. The propoed filter i imulated uing CMOS TSMC 0.8μm technology. Simulation reult are given to confirm the theoretical analyi. Keyword: Analogue filter, analogue ignal proceing, floating current ource, MOS integrated circuit Diferencialen -C paovno prehoden filter četrtega reda z uporabo izboljšanega plavajočega tokovnega vira Izvleček: Pri uporabi integriranih čaovno neomejenih filtrov e najbolj uporablja tehnika Gm-C filtrov. V članku predlagamo diferencialen Gm-C paovno prehoden filter četrtega reda z uporabo izboljšanega plavajočega tokovnega vira. Struktura izboljšanega tokovnega vira je enotavna in uporablja manj tranzitorjev, kar prinaša efektivno izrabo protora in enotavnot vezja. Itočano tudi znižuje troške. Predlagani filter ne vebuje upora, ki je potreben za integracijo. Vi kondenzatorji o ozemljeni, kar zmanjšuje parazitne vplive. Filter je imuliran v CMOS TSMC 0.8 μm tehnologiji. Podani o imulacijki rezultati, ki potrjujejo teorijo. Ključne beede: analogni filter, analogna obdelava ignalov, plavajoči tokovni vir, MOS integrirana vezja * Correponding Author ycelep@itanbul.edu.tr Introduction A continuou time filter ha been widely applied in video ignal proceing, hard dik drive, communication integrated circuit, CDMA, ultra-wideband wirele acce technology, and etc. []. -C filter are the mot popular technique ued in implementing integrated continuou-time filter []. Reearch and development in the microelectronic technology enable poibility to deign filter with le number of active and paive component. It alo bring veratility and implicity to the deign of circuit and ytem while reducing the invetment cot[3]. Motly the deired radio frequency ignal i narrowband and therefore mot of the intermediate frequencie in a uperheterodyne (uperhet) receiver deigned for application are alo narrowband. A a reult of thi important fact, band pa filter are very important building block in modern RF communication ytem. Figure how the block diagram of a typical multitep uperhet receiver with a digital back-end [4]. A the figure how, a equence of filter operation i ued to convert the deired ignal from radio frequency (RF), typically in the VHF (30 MHz to 300 MHz) range, down to one or more intermediate frequencie (IF) and finally down to baeband, where the ignal i digitized by an ADC [4]. The tudie about the 4 th order filter have been reported in the literature [-,5-9]. The comparion of 4 th order filter circuit in term of including active device and paive component are hown in Table. 37 MIDEM Society

2 F. Kaçar et al; Informacije Midem, Vol. 44, No. (04), 37 4 Figure : A typical uperheterodyne receiver [4] Thi paper propoe 4 th order differential -C bandpa filter uing improved floating current ource. Improved floating current ource performance i better than the floating current ource at low frequencie, becaue of high output reitance. Compared with the tudie that are hown in Table, the improved current ource tructure i imple and include fewer tranitor. Thu, we can ue the chip area more effective and thi bring implicity to the deign of circuit and reduce invetment cot. The improved floating current ource ha very imple tructure a hown in Figure. Having two different and it frequent ue in recent tudie make the floating current ource ueful. It i electronically adjutable uing bia current a OTA tructure. Floating current ource operation i imilar to OTA. But, there i only one for OTA and two different in floating current ource. The output reitance of the improved floating current ource i higher than the floating current ource which i propoed by Arbel and Goldminz [0]. M5, M6, M7 and M8 tranitor are added to the conventional floating current ource to get high output reitance value a hown in Figure. The high output reitance i a neceity in current-mode tructure and therefore the improved floating current ource i preferred according to conventional improved floating current ource. High output reitance provide better reult at low frequency region. Output current of the improved floating current ource i calculated by multiplying the voltage difference between P and N terminal with. The for P terminal i (g 3 /g 4 )/ and the of the n terminal i -(g +g )/. The capacitor are connected to the tructure without uing reitance and thi connection provide the deired tranfer function in filter and ocillator application [-]. In thi tudy, we propoed -C filter application. Table : The 4 th order filter tructure reported in literature Active Device Active Device Number Paive Component Number Reference DVCC 4 8 [5] OTA 6,8,8 4,4,8 [6-8] OPAMP 0 [9] Current Mirror 4 4 [] cell 8 4 [] Propoed 4th order band-pa filter tructure Figure : Schematic repreentation of improved floating current ource [] W/L of tranitor and DC value of the circuit are reported in Table and Table 3, repectively. The functionality of the propoed circuit i demontrated on a 4 th order band pa ladder filter deign which i illutrated in Figure 3 and the ladder filter component value are given in Table 4. Table : Tranitor dimenion Tranitor W(μm) L(μm) M, M M 3, M M 5, M M 7, M

3 F. Kaçar et al; Informacije Midem, Vol. 44, No. (04), 37 4 Table 3: DC value of improved floating current ource Parameter V DD, V SS ±0.9V I B, I B 300μA V B,V B 0.3V H ( ) = + C L Gm C Gm Gm3 + C C C m4 L + C L Gm6 Gm9 Gm7 m8 + CL () Center frequency of the band pa filter i given in Equation (). G G m3 m4 m7 m8 ω 0 = () C CL CL Figure 3: The LC Butterworth ladder filter Table 4: Ladder filter component value Component R, R 00Ω, 00Ω C, 5pF,.5pF L, L 5nH,.5μH The block diagram of the propoed 4 th order -C band-pa filter i preented in Figure 4. The propoed filter block diagram i the equivalent filter of the ladder filter in Figure 3 which conit of paive component. -C filter component value and performance parameter are given in Table 5. Table 5: -c filter component value and performance parameter Component C =C, C ==C C L =C L =L.( ) C L =C L =L.( ) Parameter = 3 = 4 = 5 = 6 = 7 = 8 = 9 5pF,.5pF 0,87pF 5,7 pf.64ma/v 0.99mA/V Tranfer function of the filter i given in Equation (). 3 Simulation We perform the imulation by uing LTSPICE program with TSMC CMOS 0.8 μm proce parameter. The performance parameter of improved floating current ource ued in imulation are preented in Table 6. Table 6: Performance parameter of IFCS tructure Parameter V DD, V SS ±0.9V I B, I B 300μA V B,V B 0.3V =.445mA/V Paraitic capacitance at p, n terminal 0.3pF, 5.6fF Input offet voltage 0 Power diipation 0.54mW The output current at n and p terminal of improved floating current ource againt input voltage (V Y -V Y ) are hown in Figure 5. The output current change between ±300μA. Figure 6 clearly how that the of improved floating current ource operate well at frequencie cloe to 00MHz. The ladder circuit in Figure 3 and the propoed circuit in Figure 4 are imulated with uing the component value in Table 4 and Table 5. Figure 7 illutrate Figure 4: Block diagram of 4 th order differential -C band-pa filter 39

4 F. Kaçar et al; Informacije Midem, Vol. 44, No. (04), 37 4 Figure 5: The DC tranfer characteritic of improved floating current ource Figure 7: Ideal and imulation frequency repone of 4 th order differential -C band-pa filter Figure 7 how that, the propoed filter can be ued in modern RF communication circuit a the propoed filter operate intermediate frequencie in a uperheterodyne (uperhet) receiver. The large ignal behavior of the propoed circuit band-pa filter wa teted by applying a 0 MHz inuoidal ignal with different amplitude to the input. The dependence of the output harmonic ditortion of band-pa filter on input voltage amplitude i illutrated in Figure 8. The total harmonic ditortion lowly increae (pat tene olabilir bence) depending input voltage which i lower than 400mVpp. The THD remain in acceptable limit i.e. 3 %. Thu it confirming the practical utility of the propoed circuit hown in Figure 8. Figure 6: The AC tranfer characteritic of improved floating current ource the imulation reult of ideal and propoed 4th order differential Gm-C band-pa filter. Center frequency i 30, MHz in LTSPICE imulation reult of the filter repone. We calculated theoretical centre frequency uing Equation a ω 0 =px30,05 MHz uing the value in Table 5. Simulation reult obtained from our experiment how good match with the theoretical reult. Figure 8: Total harmonic ditortion (THD) value of band-pa filter for different frequency value terminal 4 Concluion In the tudy; a fourth order differential -C band-pa filter uing improved floating current ource i preented. Floating current ource operation i imilar to OTA. But, floating current ource i uperior to the OTA a it contain two different while there i only one in OTA. The improved floating current ource ha very imple tructure. It i electronically adjutable uing bia current. The filter centre frequency i about 30MHz. Simulation reult how good match with the 40

5 F. Kaçar et al; Informacije Midem, Vol. 44, No. (04), 37 4 theoretical reult. The propoed filter operate intermediate frequencie and can be ued in modern RF communication circuit. The imulation obtained by LTSPICE indicate good functionality of the circuit, low total harmonic ditortion. The improved current ource tructure i imple and include fewer tranitor. Thu, we can ue the chip area effectively and alo bring implicity to the deign of circuit and reduce the invetment cot. The filter doe not contain reitor and all capacitor are grounded. Therefore, it i uitable for integration and le effected from paraitic. 5 Acknowledgement The author would like to thank Itanbul Univerity Reearch Fund for thi financial upport. Thi work wa partially upported by Itanbul Univerity Reearch Fund with the project code Reference. FENG, J., WANG, C., ZANG, M., REN, Y. Realization of Current-Mode General Nth-Order Filter Baed on Current Mirror. 3 rd International Conference on Advanced Computer Control (ICACC 0), 0, p BOZOMITU, R.G., CEHAN, V. A VLSI Implementation of a New Low Voltage 4 th Order Differential -C Band-Pa Filter For Different Approximation In CMOS Technology. Acta Technica Napoceni, Electronic and Telecommunication, 009, vol.50, p RANJAN, A., PAUL, S.K. Voltage Mode Univeral Biquad Uing CCCII. Active and Paive Electronic Component, 0, doi:0.55/0/ KAÇAR, F. A New Tunable Floating CMOS FDNR and Elliptic Filter Application. Journal of Circuit, Sytem, and Computer, 00, vol. 9, n.8 p ČAJKA, J., DOSTÁL, T., VRBA, K. High-Order Lowpa Filter Uing DVCC Element. Radioengineering, 00, vol., p MEHRMANESH, S., ASLANZADEH, H.A., VAHIDFAR, M.B., ATARODI, M. A.8v High Dynamic Range CMOS -C Filter For Portable Video Sytem. IEEE 4 th International Conference on Microelectronic ICM-00, 00, p LIN, J.Y., CHANG, W.H., HUNG, C.C. 5mhz Wide Tuning-Range OTA With 69db Hd3 And It Application To -C Filter. IEEE International Sympoium on VLSI Deign, Automation and Tet, 0, p STEHR, U., HENKEL, F., DALLÜGE, L., WALDOW, P. A Fully Differential CMOS Integrated 4 th Order Reconfigurable -C Lowpa Filter For Mobile Communication. ICECS 003, 003, p D AMICO, S., GIANNINI, V., BASCHIROTTO, A. A 4 th -Order Active- -RC Reconfigurable (UMTS/ WLAN) Filter. IEEE Journal Of Solid-State Circuit, 006, vol. 4, p ARBEL, A.F., GOLDMINZ, L. Output Stage for Current-Mode Feedback Amplifier, Theory And Application. Analog Integrated Circuit Signal Proce, 99, vol., p SOBHY, E. A., SOLIMAN, A.M. Novel CMOS realization of the inverting econd-generation current conveyor and application, Analog Integrated Circuit Signal Proce, 007, vol.5, p ALTUN, M., KUNTMAN, H. Deign of a Fully Differential Current Mode Operational Amplifier with Improved Input-Output Impedance and It Filter Application. AEU: International Journal of Electronic and Communication, 008, vol. 6, p Arrived: Accepted: