Voltage-mode biquadratic filters with one input and five outputs using two DDCCs

Transcription

1 ndian Jurnal f Engineering & Materials Sciences l. 8, April, pp. 97- ltage-mde biquadratic filters with ne input and five utputs using tw DDCCs Wei-Yuan Chiu & Jiun-Wei Hrng* Department f Electrnic Engineering, Chung Yuan Christian Universit, Chung-Li, 33, Taiwan Received 6 June ; accepted 3 March n this paper, tw new vltage-mde universal biquadratic filters each with ne input terminal and five utput terminals are presented. Each f the prpsed circuits can realize vltage-mde highpass, bandpass, lwpass, ntch and allpass filter transfer functins, simultaneusl, b using tw plus-tpe differential difference current cnvers (DDCCs), tw grunded capacitrs and three resistrs. Mrever, the prpsed circuits have the fllwing attractive advantages: (i) realizatin f all the standard filter functins frm the same circuit cnfiguratin, (ii) emplment f grunded capacitrs that is ideal fr integratin and (iii) lw active and passive sensitivities. Kewrds: Current cnver, Active filter, Analg signal prcessing, Universal biquad Operatinal amplifiers have traditinall plaed an imprtant rle in the design f active filters. Hwever, peratinal amplifier based circuits ften suffer frm the limited bandwidth and slew-rate. Recentl, the current cnvers as active elements received cnsiderable attentin due t higher signal bandwidth, wider dnamic range, greater linearit and simpler circuitr ver the vltage-mde peratinal amplifiers. Analg filters perfrm ne f the mst imprtant functins f present da electrnics sstems. These have been used in man applicatins in cmmunicatins, cntrl sstems and bimedical. T btain varius filter functins in the same circuit tplg simultaneusl will increase the usabilit and reduce the cst f the circuit. Fr abve reasns, man multifunctin biquadratic filters were prpsed based n current cnvers 3-. Sme multifunctin biquadratic filters with single input and three utputs that can realize highpass, bandpass and lwpass filters, simultaneusl, were prpsed in references 3-6. Hwever, the circuit cnfiguratins in references 3,4 required at least three active cmpnents. Chang and Lee 5 and Hrng et al. 6 prpsed a vltage-mde multifunctin biquadratic filter that can realize highpass, bandpass and lwpass filters, simultaneusl, b using nl tw current cnvers. Hwever, the ntch and allpass filter signals cannt be simultaneusl btained. Sme multifunctin biquadratic filters with single input and tw utputs *Crrespnding authr ( jwhrng@ccu.edu.tw) that can realize highpass and bandpass r bandpass and lwpass filters, simultaneusl, were prpsed in reference 7. Hwever, nl tw standard filter functins be simultaneusl btained. Abuelma atti and Al-Zaher 8 prpsed a circuit cnfiguratin with ne input terminal and five utput terminals using five current feedback amplifiers (CFAs), tw grunded capacitrs and si resistrs. Hrng et al. 9, prpsed anther si circuit cnfiguratins with ne input terminal and five utput terminals. Each f the circuits in reference 9 empled three (r fur) multiple utput secnd-generatin current cnvers (MOCCs), tw grunded capacitrs and si (r seven) resistrs. n reference, each f the first tw circuits empled fur secnd-generatin current cnvers (CCs), tw grunded capacitrs and five resistrs; the third circuit empled tw CCs, ne differential vltage current cnver (DCC), tw grunded capacitrs and five resistrs; the furth circuit empled tw MOCCs, tw grunded capacitrs and five resistrs. Althugh each f these circuits 8- can realize the entire standard filter functins (lwpass, bandpass, highpass, ntch, and allpass) simultaneusl, these circuits empled etra active r passive cmpnents. Chen prpsed a circuit cnfiguratin with ne input terminal and five utput terminals using tw full differential current cnvers (FDCCs), tw grunded capacitrs and tw grunded resistrs. Hwever, the FDCC is a ver cmplicate device. On each FDCC there are almst twice as man MOSs as ne differential

2 98 NDAN J EN. MATER. SC., APRL difference current cnver (DDCC) needs. Mrever, the prt relatins f a FDCC are equivalent t the prt relatins f tw DDCCs arithmeticall. n this paper, tw new vltage-mde universal biquadratic filters with single input terminal and five utput terminals are presented. Each f the prpsed circuits can realize vltage-mde highpass, bandpass, lwpass, ntch and allpass filter transfer functins, simultaneusl, b empling tw plus-tpe DDCCs, tw grunded capacitrs and three resistrs. The use f nl grunded capacitrs is particularl attractive fr integrated circuit implementatin 3. Since the implementatin cnfiguratin f the plus-tpe DDCC is simpler than that f the minus-tpe DDCC, the prpsed universal filters empl nl plus-tpe DDCCs. Simulatin results are included t verif the theretical analses. The Prpsed Circuits The DDCC was prpsed in 996, and it enjs the advantages f the CC (such as higher signal bandwidth, wider dnamic range, greater linearit) and differential difference amplifier (DDA). Using standard ntatin, the prt relatins f an ideal plustpe DDCC can be characterized b 3 z zk 3 () The first prpsed cnfiguratin is shwn in Fig.. The transfer functins can be epressed as ut s CC in + + s C C sc sc ut in s CC + sc + s C C sc ut3 in + + ut 4 + in s CC + sc + s C C ut in s C C 5 3 s + sc C C + sc sc + + () (3) (4) (5) (6) Frm Eqs ()-(6) it can be seen that a highpass respnse is btained frm ut, a bandpass respnse is btained frm ut, a lwpass respnse is btained frm ut3, a ntch respnse is btained frm ut4 and if 3, an allpass respnse is btained frm ut5. n all cases the resnance angular frequenc and the qualit factr are given b CC RR (7) and C R (8) CR The secnd prpsed cnfiguratin is shwn in Fig.. The transfer functins can be epressed as Fig. The first prpsed vltage-mde biquadratic filter Fig. The secnd prpsed vltage-mde biquadratic filter

3 CHU & HORN: OLTAE-MODE UNERSAL BUADRATC FLTERS 99 ut s CC in + + s C C sc sc ut in s CC + sc + s C C sc ut3 in + + ut 4 + in s CC + sc + s C C (9) () () () in + + s C C sc sc 3 ut 5 s C C + sc + (3) Fig. 3 CMOS realizatin f the plus-tpe DDCC Frm Eqs (9)-(3) it can be seen that a highpass respnse is btained frm ut, a bandpass respnse is btained frm ut, a lwpass respnse is btained frm ut3, a ntch respnse is btained frm ut4 and if 3, an allpass respnse is btained frm ut5. n all cases the resnance angular frequenc and the qualit factr are given b and (4) CR (5) C R Each f the prpsed circuits in Figs and can realize vltage-mde highpass, bandpass, lwpass, ntch and allpass filter transfer functins, simultaneusl, b empling tw plus-tpe DDCCs, tw grunded capacitrs and three resistrs. The uses f grunded capacitrs are ideal fr integrated circuit implementatin 3. The prpsed circuits empl fewer active r passive cmpnents with respect t the previus ne input and five utputs universal biquadratic filters 8-. The prpsed circuits empl simpler active elements with respect t the vltagemde ne input and five utputs universal biquadratic filter. Since the utput impedances f the prpsed circuits are nt small, vltage buffers are needed while cascaded the prpsed circuits t the net stages. Sensitivities Analsis Taking the nn-idealities f the plus-tpe DDCC int accunt, the relatinship f the terminal vltages and currents can be rewritten as Z 3 Zm α k(s) α (s) k α k 3 (s) β k( s) β km 3 (6) where α k ( s ), α k and α k3 ( s ) represent the frequenc transfer functins f the internal vltage fllwers and β k (s) represent the frequenc transfer functin f the internal current fllwer f the k th DDCC. The can be apprimated b first rder lwpass functins, which can be cnsidered t have a unit value fr frequencies much lwer than their crner frequencies 4. f the circuit is wrking at frequencies much lwer than the crner frequencies f α k ( s ), α k ( s ), α k3 and β k (s ), then ak αk εk v and ε kv ( ε kv <<) dentes the vltage tracking errr frm terminal t terminal

4 NDAN J EN. MATER. SC., APRL f the k th DDCC, αk αk ε kv and ε kv ( ε kv <<) dentes the vltage tracking errr frm terminal t terminal f the k th DDCC, αk3 αk3 εk3v and ε ( ε k3v k3v <<) dentes the vltage tracking errr frm 3 terminal t terminal f the k th DDCC and β k (s) β k ε ki and ε ki ( ε ki <<) dentes the current tracking errr f the k th DDCC. The denminatr f the transfer functins in Fig. becmes D(s) s CC + scα β + α3αββ (7) The and are btained b α3αββ (8) CRα 3αβ (9) α C R β Taking the tracking errrs f the plus-tpe DDCCs int accunt, the denminatr f the transfer functins in Fig. becmes D(s) s C C + sc α α β + () α α β β 3 The and are btained b αα 3ββ () CRα 3β () α C Rα β The passive and active sensitivities have been fund using Eqs (7)-() and are listed in Table. t can be fund easil that the active and passive sensitivities f and are n mre than unit in magnitude withut critical cmpnent-matching cnditins. Therefre, all the prpsed circuits enj attractive sensitivities perfrmance. Fig. 4 (a) Simulated amplitude-frequenc respnses fr the highpass ( ut ), bandpass ( ut ), lwpass ( ut3 ), ntch ( ut4 ) and allpass( ut5 ) filter f Fig. and (b) simulated phase-frequenc respnses fr the highpass ( ut ), bandpass ( ut ), lwpass ( ut3 ), ntch ( ut4 ) and allpass ( ut5 ) filter f Fig. Simulatin Results T verif the theretical analsis, the prpsed circuits were simulated using HSPCE with TSMC.5 µm CMOS technlg prcess parameters. The DDCC was realized b the CMOS implementatin in Fig. 3 4 with the NMOS and PMOS transistr aspect ratis W/L5µ/.5µ and W/Lµ/.5µ, respectivel. The pwer suppl was ±.5 and the biasing vltage b was taken as.75. Figures 4a and 4b represent the simulated amplitude-frequenc respnses and phase-frequenc respnses fr the highpass, bandpass, lwpass, ntch and allpass filters f Fig. designed with and f.59 MHz, C C pf and R R kω 3 k Ω. Figures 5a and 5b represent the simulated amplitude-frequenc respnses

5 CHU & HORN: OLTAE-MODE UNERSAL BUADRATC FLTERS Table The active and passive sensitivities f the prpsed filters Figure Active sensitivities Passive sensitivities Fig. S α 3, α S C, C S α, α S 3 β, Sα C S C Fig. S α, α 3 S C, C S α S 3 α, Sα S C S C Cnclusins Tw new vltage-mde universal biquadratic filters with ne input terminal and five utput terminals are presented. Each f the prpsed circuits can realize vltage-mde highpass, bandpass, lwpass, ntch and allpass filter transfer functins, simultaneusl, b using tw plus-tpe DDCCs, tw grunded capacitrs and three resistrs. The prpsed circuits empl less active r passive cmpnents with respect t the previus vltage-mde ne input and five utputs universal biquadratic filters 8-. The prpsed circuits empl simpler active elements with respect t the vltage-mde ne input and five utputs universal biquadratic filter. Fig. 5 (a) Simulated amplitude-frequenc respnses fr the highpass ( ut ), bandpass ( ut ), lwpass ( ut3 ), ntch ( ut4 ) and allpass ( ut5 ) filter f Fig. and (b) simulated phase-frequenc respnses fr the highpass ( ut ), bandpass ( ut ), lwpass ( ut3 ), ntch ( ut4 ) and allpass( ut5 ) filter f Fig. and phase-frequenc respnses fr the highpass, bandpass, lwpass, ntch and allpass filters f Fig. designed with and f.6 MHz, C C pf and R R 5 k Ω 3 3 k Ω. References Wilsn B, EE Prc-Circuits Devices & Sst, 37 (99) Tumazu C, Lidge F J & Haigh D, Analgue C Design: The Current-Mde Apprach, (Peter Peregrinus, Lndn, UK), Hrng J W, La J R, Chang C W & Lee M H, Electrn Lett, 33 (997) Hrng J W & Lee M H, Electrn Lett, 33 (997) Chang C M & Lee M J, EEE Trans Circuits Sst, 46 (999) Hrng J W, Chiu W Y & Wei H Y, nt J Electrn, 9 (4) Hrng J W, nt J Electrn, 86 (999) Abuelma atti M T & Al-Zaher H A, Analg ntegrated Circuits Signal Prcess, 6 (998) Hrng J W, Hu C L, Chang C M, Chung W Y & Wei H Y, Cmput Electr Eng, 3 (5) 9-. Hrng J W, Hu C L, Chang C M & Chung W Y, Analg ntegrated Circuits & Signal Prcess, 47 (6) Chen H P, nt J Electrn Cmmun (AEÜ), 6 (8) Chiu W, Liu S, Tsa H W & Chen J J, EE Prc-Circuits Devices Sst, 43 (996) Bhushan M & Newcmb R W, Electrn Lett, 3 (967) Elwan H O & Sliman A M, EE Prc, Pt, 44 (997)95-.