Extremely low-voltage low-power differential difference current conveyor using multiple-input bulk-driven technique

Ex emely low- ol age low-powe di e en ial di e ence cu en con eyo using mul iple-inpu bulk-d i en echnique KUMNGERN, M.; KHATEB, F.; KULEJ, T. AEU - In e na ional Jou nal o Elec onics and Communica ions 2020, ol. 123, Augus 2020, pp. 1−11 ISSN: 1434-8411 DOI: h ps://doi.o g/10.1016/j.aeue.2020.153310 Accep ed manusc ip © 2020. This manusc ip e sion is made a ailable unde he CC-BY-NC-ND 4.0 license h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/ dspace. u b .cz Ex emely low- ol age low-powe di e en ial di e ence cu en con eyo using mul iple-inpu bulk-d i en echnique Mon ee Kumnge n1, Fabian Kha eb2,3, Tomasz Kulej4 1 Depa men o Telecommunica ions Enginee ing, Facul y o Enginee ing, King Mongku ’s Ins i u e o Technology Ladk abang, Bangkok 10520, Thailand 2 Depa men o Mic oelec onics, B no Uni e si y o Technology, Technická 10, B no, Czech Republic 3 Facul y o Biomedical Enginee ing, Czech Technical Uni e si y in P ague, nám. Sí ná 3105, Kladno, Czech Republic 4 Depa men o Elec ical Enginee ing, Czes ochowa Uni e si y o Technology, 42-201 Czes ochowa, Poland [email p o ec ed], kha eb@ eec. u b .cz, [email p o ec ed] Abs ac In his pape , a new di e en ial di e ence cu en con eyo (DDCC) wi h ul a-low ol age and low-powe capabili y is p esen ed. The DDCC is designed by using a non- ailed di e en ial pai wi h mul iple-inpu bulk-d i en MOS ansis o echnique o ob ain a ail- o- ail inpu common-mode swing and ex emely low supply ol age. The MOS ansis o s biased in he sub- h eshold egion ha e been used o achie e ex emely low powe consump ion. The pe o mance o he p oposed DDCC is e alua ed by simula ion esul s using SPICE p og am and MOS ansis o s pa ame e s p o ided by a s anda d n-well 0.18 µm CMOS p ocess om TSMC. A ail- o- ail inpu common-mode ange was shown and a high accu acy was exp essed. The bandwid h was 2.2 kHz and he o al ha monic dis o ion was 1 % o an inpu signal wi h ampli ude o 240 mVp-p, ob ained a supply ol age o 0.3 V and powe dissipa ion o 28.6 nW. The p oposed DDCC has been used o ealize a six h-o de low-pass il e o applica ion o elec oca diog am (ECG) applica ions. Keywo ds: Di e en ial di e ence cu en con eyo ; sub h eshold echnique; bulk-d i en echnique; mul iple-inpu bulk-d i en echnique; low ol age and low powe ; high-o de il e ; analog ci cui 1. In oduc ion The second gene a ion cu en con eyo (CCII) is a basic building block which can ind many applica ions in analog signal p ocessing applica ions such as con inuous- ime il e s, signal gene a o s, nonlinea ci cui s, elec ical elemen s ( esis ance, induc ance, mem is ance) simula o s/emula o s ci cui s and da a con e e s [1]-[7]. In compa ison o ope a ional ampli ie (op-amp)-based ci cui s, CCII-based ci cui s o e se e al ad an ages: simple ci cui s uc u e, alle ia ing he need o bo h loa ing passi e componen s and ma ched esis o s, wide equency bandwid h, e sa ile and high accu acy in ealizing he in ended cha ac e is ics, la ge dynamic ange and low supply ol age equi emen [8]. A numbe o CCIIs is a ailable in open li e a u e [9]-[19]. The ea ly s uc u e o CCII is a con en ional CCII which o e s h ee e minals, namely y-, x- and z- e minals [9]. The uni y ol age gain can be ob ained be ween y- and x- e minals while he uni y cu en gain can be ob ained be ween x- and z- e minals. Howe e , a single CCII may be limi ed o some applica ions: ob aining di e en ial ol age o cu en inpu signals equi emen s, posi i e and nega i e o eedback connec ions and alle ia ing he need o loa ing esis o s, e c. The e o e, he e a e se e al s uc u es o CCIIs which ha e been de eloped o inc ease he pe o mance o con en ional CCII: di e en ial di e ence cu en con eyo (DDCC) [10], di e en ial ol age cu en con eyo (DVCC) [11], dual X second gene a ion cu en con eyo (DX-CCII) [12], ex a X second gene a ion cu en con eyo (EX-CCII) [13], di e en ial second gene a ion cu en con eyo (DCCII) [14], ully di e en ial second-gene a ion cu en con eyo (FDCCII) [15]. These s uc u es imp o ed he pe o mance o con en ional CCII, which has one y- e minal, one x- e minal and one z- e minal, by adding y- e minal and/o x- e minal o ob ain adding/sub ac ing ol age and cu en di e encing capabili y. This wo k ocuses on he DDCC which p o ides he ad an ages o con en ional CCII and a i hme ic ope a ion capabili y o di e en ial di e ence ampli ie (DDA) [16] in o single de ice. Thus, he con en ional DDCC has h ee y- e minals, one x- e minal and one z- e minal, whe e adding and sub ac ing ol age can be ob ained h ough wo plus- ype y- e minals and one minus- ype y- e minal. The DDCC wi h bo h plus- ype and minus- ype y- e minals is con enien o ealizing posi i e and nega i e eedback applica ions such as nega i e eedback o il e s and posi i e eedback o oscilla o s. The e a e DDCC based analogue ci cui s ha ha e been epo ed in li e a u e in ecen yea s, o example, see [17]–[21]. Un o una ely, hese ci cui s do no p o ide ul a-low ol age and ul a-low powe ope a ion. A p esen , he analogue ci cui s ope a ing wi h ul a-low supply ol age and ul a-low powe consump ion a e o g own in e es , due o he ac ha hese ci cui s can be applied in po able elec onics and biomedical de ices [22]. The analogue signal p ocessing ci cui s such as con inuous- ime il e s [23]–[25], ampli ie s [26]-[27], p ecision ec i ie s [28]–[29], a e usually equi ed o applica ions. The e a e many ac i e de ices ope a ing wi h ul a-low supply ol age and ul a-low powe consump ion a ailable in open li e a u e such as ope a ional ansconduc ance ampli ie s (OTAs) [30]–[32], cu en con eyo s [33]–[34], DDA [35] e c. Focusing on DDCC ope a ed wi h ul a-low supply ol age and ul a-low powe consump ion, his de ice has been al eady in oduced using di e en MOS echniques [36]– [41]. Se e al DDCCs based on bulk-d i en (BD) MOS echnique [36], [37], quasi- loa ing ga e (QFG) [36], BD QFG MOS echnique [36], [38], mul iple-inpu bulk-d i en (MIBD) QFG MOS echnique [39], [40], mul iple-inpu bulk-d i en (MIBD) [40], ha e been p oposed. I conside he supply ol age and powe consump ion, he ci cui s in [36], [37] use 0.6 V (±0.3) o supply ol age and consume abou 18.5 µW o powe , he ci cui in [38] uses a 1 V o supply ol age and consumes 37 µW o powe , he ci cui in [39] uses a 0.5 V o supply ol age and consumes 1.7 µW and he ci cui s in [40] uses a 0.4 V o supply ol age and consumes 0.14 µW o powe . I should be no ed in [36]–[40] ha he supply ol age and powe consump ion, espec i ely, o DDCCs a e scaled down om 1 V o 0.4 V and 37 µW o 0.14 µW. Un il now, DDCC ope a ing wi h 0.3 V supply ol age and consuming 38 nW o powe is in oduced [41]. The inpu s age o DDCCs in [36]–[40] is ealized based on di e en ial s uc u e which needs a ail cu en . A ail cu en is usually implemen ed by a MOS ansis o , which inc eases he minimum supply ol age by a leas 𝑉𝐷𝑆(𝑠𝑎𝑡). Thus, he lowes supply ol age o hese DDCCs [36]–[40] is a ound 0.4 V [40]. Unlike he DDCCs in [36]–[40], he DDCC in [41] is based on a non- ailed di e en ial ampli ie , and is able o ope a e om supply ol age as low as 0.3 V, which canno be achie ed o a DDCC wi h a ail cu en di e en ial ampli ie . The ci cui in [41] can ope a e wi h ex emely low supply ol age, bu shows ela i ely poo accu acy o he ol age/cu en gains, which is he esul o i s simple s uc u e and low open-loop ol age gain o he y-x ampli ie . This also esul s in ela i ely low alue o he esis ance Rx, seen om i s x e minal. In o de o o e come he abo e issues, a high pe o mance DDCC which can ope a e wi h ul a-low supply ol age and ul a-low powe consump ion has been p oposed in his pape . The p oposed DDCC can ope a e om supply ol age as low as 0.3-V, which is possible hanks o he use o non- ailed di e en ial pai in i s inpu s age. The mul iple-inpu bulk-d i en echnique is also used o educe a numbe o MOS di e en ial pai s. The DDCC shows ul a-low supply ol age and ul a-low powe consump ion using h ee echniques, namely, sub h eshold biasing, dynamic h eshold MOS and bulk-d i en MOS echniques. The bulk-d i en echnique is used in he inpu s age and hanks o his a ail- o- ail inpu common- mode ange can be ob ained. The pe o mance o he p oposed DDCC was e alua ed by simula ion, using SPICE and ansis o s pa ame e s o a s anda d n-well 0.18 µm CMOS p ocess om TSMC. Simula ions showed he bandwid h o 2.2 kHz and he o al ha monic dis o ion o 1 % o an inpu signal wi h ampli ude o 240 mVp-p, ob ained a supply ol age o 0.3 V and powe dissipa ion o 28.6 nW. The p oposed DDCC has been used o ealize a six h-o de low-pass il e o elec oca diog am (ECG) applica ions. 2. P oposed ul a-low ol age MIBD DDCC In his wo k he mul iple-inpu bulk-d i en (MIBD) MOS ansis o (MOST) echnique, [40] was applied. The symbol and implemen a ion o he MIBD MOS a e shown in Figs. 1(a) and Fig. 1(b) espec i ely. The MIBD MOST is a mul iple-inpu de ice which is ealized using pa allel connec ions o capaci o s CBi and esis o s RLi, whe e i = 1, 2, …, N, while i s ga e e minal is p ope ly biased wi h DC ol age Vb. Assuming ha an n-well CMOS p ocess was applied in he design , only he p-channel MOS ansis o s can be con olled in such a way. The esis o RL should possess high esis ance alue which can be implemen ed using wo ansis o s ML ope a ing in cu -o egion as shown in Fig. 1(b). The small-signal model o he MIBD MOST ha has been used o AC small-signal analysis is shown in Fig. 1(c). The gmb is he bulk ansconduc ance, o is he ou pu esis ance, he capaci ances CBS, CBD, CBSUB a e espec i ely he pa asi ic capaci ances bulk-sou ce, bulk-d ain and bulk-subs a e. The capaci ance CMi is he pa asi ic capaci ance be ween ga e and d ain o he ansis o MLi, he esis ance RMi is he ou pu esis ance o he ansis o MLi while he capaci ance CBi is he inpu capaci ance. GVin1 S D VinN BVb (a) CB1 S D B Vin1 VinN CBN GVb RL1 RLN ML ML (b) CBS VinN CBD RMN CMN CBN Vin1 CM1 CB1 RM1 B CBSUB Sub D o gmbVBS S (c) Fig. 1. MIBD PMOST [40]: (a) symbol o MIBD, (b) MIBD implemen a ion, (c) small-signal model. F om Fig. 1(c), assuming 1/CBi << RLi, CMi << CBi he inpu ansconduc ances (𝑔𝑚𝑖) o MIBD MOST can be gi en [40] by 𝒈𝒎𝒊=𝑪𝑩𝒊 𝑪𝑻𝑶𝑻𝒈𝒎𝒃 (1) whe e 𝑪𝑻𝑶𝑻 is he o al capaci ance looking in o inpu po which can be gi en by 𝑪𝑻𝑶𝑻=𝑪𝑩𝑺+𝑪𝑩𝑫+𝑪𝑩𝑺𝑼𝑩+∑𝑪𝑴𝒊+ 𝑵 𝒊=𝟏 ∑𝑪𝑩𝒊 𝑵 𝒊=𝟏 (2) The ol age a bulk e minal 𝑽𝑩 can be gi en by 𝑽𝑩≈∑𝑪𝑩𝒊 𝑪𝑻𝑶𝑻𝑽𝒊𝒏,𝒊 𝑵 𝒊=𝟏 (3) The ela ion be ween he inpu s- e e ed noise powe s o he MIBD MOST 𝒗𝒏,𝒊 𝟐      compa ed o he BD MOST 𝒗𝒏,𝑩 𝟐      can be exp essed by 𝒗𝒏,𝒊 𝟐      =(𝑪𝑻𝑶𝑻 𝑪𝑩,𝒊)𝟐𝒗𝒏,𝑩 𝟐      (4) whe e 𝑪𝑻𝑶𝑻 is he o al capaci ance looking in o he inpu po . I can be concluded om (4) ha he inpu - e e ed noise o he MIBD MOST is inc eased by 𝑪𝑻𝑶𝑻 𝑪𝑩,𝒊 ⁄, bu he maximum inpu signal ange is also inc eased wi h he same a io, hence he dynamic ange (DR) is no a ec ed by his a io. Fig. 2 shows he ci cui symbol o DDCC and i s po ela ions can be exp essed by ( 𝑰𝒚𝟏 𝑰𝒚𝟐 𝑰𝒚𝟑 𝑽𝒙 𝑰𝒛 ) = ( 𝟎 𝟎 𝟎 𝜷𝟏 𝟎 𝟎 𝟎 𝟎 −𝜷𝟐 𝟎 𝟎 𝟎 𝟎 𝜷𝟑 𝟎 𝟎 𝟎 𝟎 𝟎 𝜶 𝟎 𝟎 𝟎 𝟎 𝟎 ) ( 𝑽𝒚𝟏 𝑽𝒚𝟐 𝑽𝒚𝟑 𝑰𝒙 𝑽𝒛 ) (5) whe e 𝛽1=1−𝜀1𝑣, 𝛽2=1−𝜀2𝑣, 𝛽3=1−𝜀3𝑣 ep esen he ol age gain be ween x- e minal and y1-, y2-, y3- e minals, espec i ely, 𝛼=1−𝜀𝑖 ep esen s he cu en gain be ween z- e minal and x- e minal, whe eas 𝜀1𝑣, 𝜀2𝑣, 𝜀3𝑣 (|𝜀1𝑣|, |𝜀2𝑣|, |𝜀3𝑣|≪1 and |𝜀𝑖|≪1) ep esen espec i ely ol age and cu en acking e o s. Fo ideal case, 𝛽1= 𝛽2= 𝛽3= 𝛼 =1. DDCC y1 z Vy1 Vz Iz x Vx Ix y3 Vy3 y2 Vy2 Iy2 Iy3 Iy1 Fig. 2. Elec ical symbol o DDCC. VSS VDD M1y2y3 y3 M5M6 VB M9M10 M13 M11 M16 VB IB MB VB VSS zx y2 M2M4M3 M7 M12 M8 M14 M17 M18 y1 M15 Fig. 3. P oposed 0.3 V MIBD DDCC. The p oposed in e nal s uc u e o he DDCC is shown in Fig. 3. The ansis o s, M1- M6, o he ci cui o m a non- ailed bulk-d i en di e en ial ampli ie [42] which is ealized using he MIBD MOST echnique o ob ain mul iple-inpu di e en ial ampli ie and o educe a numbe o MOS ansis o pai s. This non- ailed a chi ec u e p o ides a good CMRR [32], [35], [42], which can imp o e he accu acy o DDCC when i is connec ed in a nega i e eedback uni y-gain con igu a ion. The non- ailed di e en ial ampli ie p o ides an ul a-low supply ol age o he ci cui because he ol age ac oss ail cu en sou ce is absen [35]. The c oss-coupled ansis o s M7 and M8 a e added o o m a posi i e eedback and p o ide some inc emen o he DC gain and gain bandwid h p oduc (GBW) pe o mance o di e en ial ampli ie . These ansis o s will gene a e nega i e conduc ance, i.e. -gm7 and -gm8, o dec easing he o al conduc ance a he d ain e minals o M9 and M10. The diode-connec ed ansis o s M9 and M10 a e used o he load o di e en ial ampli ie which dec easing he o al conduc ance by -gm7 and -gm8 and consequen ly o imp o ing he DC gain and GBW o di e en ial ampli ie [35]. The ansis o s M11-M14 a e used o mi o he ou pu cu en s o di e en ial ampli ie and con e ed cu en signals in o a single ol age a he d ain e minals o M13 and M14. The ou pu s age consis s o ansis o s M15-M18 when ansis o s M15 and M16 wo k as ou pu ampli ie ope a ing in class-AB, loaded wi h he cu en sou ce using ansis o s M17 and M18. The high cu en d i ing capabili y can be ob ained by inc easing he quiescen d ain cu en s o M17 and M18. To ob ain a uni y-gain ol age ollowe , he ou pu e minal (d ain o ansis o M15) is connec ed o he inpu bulk e minals o ansis o s M2 and M3 hus o ming a nega i e eedback loop. The uni y-gain cu en ollowe can be ob ained using complemen a y ansis o s M16 and M18 o mi o he cu en om x- e minal o z- e minal. The minimum supply ol age 𝑽𝑫𝑫min(𝐢𝐧) o he inpu s age is gi en by 𝑽𝑫𝑫𝐦𝐢𝐧(𝐢𝐧)=𝐦𝐚𝐱(𝑽𝑮𝑺,𝑴𝒊+𝑽𝑫𝑺(𝒔𝒂𝒕),𝑴𝒋) (6) whe e 𝑖 = 2, 4, 9, 10 and 𝑗 = 1, 3, 5, 6. Le ing 𝑉𝐷𝑆(sa ) = 𝑉𝐷𝑆(𝑠𝑎𝑡),𝑀15−𝑀18, he minimum supply ol age 𝑉𝐷𝐷min(ou ) o he ou pu s age is app oxima ely 𝑉𝐷𝐷min(ou ) = 2𝑉𝐷𝑆(sa ). Assume ha ci cui is biased in sub- h eshold egion and le ing |𝑉𝐺𝑆|,𝑀2−𝑀4 = 𝑉𝐺𝑆,𝑀9−𝑀10 = 𝑉𝐷𝑆(sa ), he 𝑽𝑫𝑫min o bo h inpu and ou pu s ages is 2𝑉𝐷𝑆(sa ) which is app oxima ely equal o 6 o 8 𝑈𝑇 [35], whe e 𝑈𝑇 is abou 26 mV a oom empe a u e. Assuming pe ec symme y o he i s s age (M1 – M14), he ol age ans e a ios 𝛽1, 𝛽2, 𝛽3, can be exp essed by: 𝜷𝒊=𝑽𝒙 𝑽𝒚𝒊 =𝑨𝒐𝒊 𝟏+𝑨𝒐𝒊 (7) whe e 𝐴𝑜𝑖 (𝑖 = 1…3) is he open-loop ol age gain o he in e nal di e en ial di e ence ampli ie (M1-M15 and M17) om 𝑖 - h inpu , ha is gi en by: 𝑨𝒐𝒊=𝒈𝒎𝒊 𝒈𝒅𝒔𝟏𝟑+𝒈𝒅𝒔𝟏𝟒∙𝒈𝒎𝟏𝟓 𝒈𝒅𝒔𝟏𝟒+𝒈𝒅𝒔𝟏𝟓 (8) whe e, 𝑔𝑑𝑠𝑖 and 𝑔𝑚𝑖 a e espec i ely he ou pu conduc ance and he ga e ansconduc ance o Mi espec i ely (𝑖 = 1…N). The ansconduc ance gmi ep esen s he ansconduc ance o he i s s age om i- h inpu , which can be app oxima ed as: 𝒈𝒎𝒊≅𝟐𝒈𝒎𝒃𝟏,𝟑 𝒈𝒎𝟏𝟐,𝟏𝟒/𝒈𝒎𝟗,𝟏𝟎 (𝟏−𝒎)+𝒈∑/𝒈𝒎𝟗,𝟏𝟎∙(𝑪𝑩𝒊 𝑪𝑻𝑶𝑻) (9) whe e gmbi deno es he bulk ansconduc ance o Mi, m=gm7,8/gm9,10, g= gds1,3 +gds7,8 +gds9,10. The cu en ans e a io α o he o e all DDCC can be exp essed as: 𝜶=𝒈𝒎𝟏𝟔 𝒈𝒎𝟏𝟓 (10) The open-loop bandwid h o he in e nal di e en ial-di e ence ampli ie men ioned abo e is limi ed mainly by he h ee pa asi ic poles associa ed wi h in e nal nodes o his ci cui . The i s pole is associa ed wi h he d ain node o M9 (M10): 𝒑𝟏=−𝒈𝒎𝟗,𝟏𝟎[(𝟏−𝒎)+𝒈∑/𝒈𝒎𝟗,𝟏𝟎] 𝑪∑𝟏 ∙(𝑪𝑩𝒊 𝑪𝑻𝑶𝑻) (11) whe e C1 is he o al capaci ance associa ed wi h his node. The second pole is associa ed wi h he ou pu o he i s gain s age (d ain e minal o M13): 𝒑𝟐=−(𝟏+ 𝒈𝒎𝟏𝟓 𝒈𝒅𝒔𝟏𝟓+𝒈𝒅𝒔𝟏𝟕)𝑪𝒈𝒅𝟏𝟓+𝑪∑𝟐 (12) whe e C2 is he o al capaci ance associa ed wi h his node, excep Cgd15. The hi d pole is associa ed wi h he x e minal o he DDCC: 𝒑𝟑=−𝒈𝒎𝟏𝟓 𝑪𝒙 (13) whe e Cx is he o al capaci ance associa ed wi h he x e minal. Assuming ha he DDCC is p ope ly equency compensa ed, he poles p1 and p3 should be loca ed well abo e he 3-dB equency o he y-x ollowe . In such a case, he 3-dB equency o he ol age gain o his ollowe is app oxima ely equal o he GBW p oduc o he in e nal di e en ial-di e ence ampli ie men ioned ea lie and can be app oxima ed as: 𝒇𝟑𝒅𝑩=𝒈𝒎𝒊 𝑪𝒈𝒅𝟏𝟓 (14) The 3-dB equency o he x-z cu en ollowe is also limi ed by he abo e men ioned e ec s, and o y and z e minals sho ed o g ound o AC signals can be app oxima ed by (14) as well. The i- h inpu e e ed he mal noise o he p oposed DDCC can be app oxima ed by: 𝑣𝑛2    =1 2∙8𝑘𝑇 3(𝑔𝑚𝑏1,3 2)[𝑔𝑚1,3+(𝑔𝑚2,4+𝑔𝑚5,6)(𝑔𝑚1,3 𝑔𝑚2,4)2+𝑔𝑚7,8+𝑔𝑚9,10+(1− 𝑚)2(𝑔𝑚9,10 𝑔𝑚12,14)2(𝑔𝑚12,14+𝑔𝑚11,13)](𝐶𝑇𝑂𝑇 𝐶𝐵,𝑖)2 (15) I is wo h no ing, ha he op imum noise pe o mance is ob ained when all ansis o s M1-M4 a e iden ical [42]. The inpu esis ance seen om he x- e minal can be app oxima ed as: 𝑹𝒙≈𝒓𝒅𝒔𝟏𝟒‖𝒓𝒅𝒔𝟏𝟓 𝑨𝒐𝒊 (16) whe e i is assumed ha Aoi is iden ical o e e y i=1..3. Finally, he ou pu esis ance o he DDCC seen om he z- e minal is gi en by: DDCC y1z x y3 y2 R1 R2 DDCC y1z x y3 y2 C1 R2 C2 DDCC y1z x y3 y2 R3 R4 DDCC y1z x y3 y2 C3 R4 C4 DDCC y1z x y3 y2 R5 R6 DDCC y1z x y3 y2 C5 R6 C6 Vou - Vou + Vin+ Vin- Fig. 9. Six h-o de Bu e wo h low-pass il e . The six h-o de maximally la low-pass il e was designed by cascading h ee second-o de low-pass il e s, which a e a anged as ollows: s age 1, equency scaling ac o (FSF) = 1, Q = 0.518: s age 2, FSD = 1, Q = 0.707: s age 3, FSF = 1, Q = 1.932. The e o e, he no malized ans e unc ion o six h-o de Bu e wo h low-pass il e is: 𝑉𝑜𝑢𝑡(𝑠) 𝑉𝑖𝑛(𝑠) =( 1 𝑠2+1.93𝑠+1)( 1 𝑠2+1.414𝑠+1)( 1 𝑠2+0.518𝑠+1) (19) The p oposed six h-o de Bu e wo h low-pass il e was designed wi h he cu -o equency 𝑓𝑜 o 100 Hz. The i s s age, second s age and he hi d s age we e designed wi h he cu -o equencies o 70 Hz, 100 Hz and 148 Hz, espec i ely. The alue o capaci ances C1 and C2 o each s age will be equalled and he alue o esis ances R1 and R2 o each s age will be used o adjus he alue o quali y ac o . Thus he il e in Fig. 9 was designed as ollows: 𝐶1 = 𝐶2 = 300 pF, 𝑅1 = 5.8 M, 𝑅2 = 3 M, 𝐶3 = 𝐶4 = 220 pF, 𝑅3 = 5.8 M, 𝑅4 = 2.5 M, 𝐶5 = 𝐶6 = 220 pF, 𝑅5 = 1.8 M, 𝑅6 = 14 M. In p ac ice, hese high alues o esis ances and la ge alues o capaci ance can be implemen ed o -chip. The high alues o esis ances we e used because he high linea i y and wide inpu ange o il e can be ob ained. 1.0 10 100 1.0k 10k -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 F equency, Hz Gain, dB P oposed Theo e ical Fig. 10. Simula ed equency esponse o he six h-o de Bu e wo h low-pass il e . 1.0 10 100 1.0k 10k -180 -160 -140 -120 -100 -80 -60 -40 -20 0 20 F equency, Hz Gain, dB Theo e ical Temp.=0-75°C 10 100 300 -10.0 -7.5 -5.0 -2.5 0 F equency, Hz Gain, dB Zooming Fig. 11. Simula ed equency esponse o he six h-o de Bu e wo h low-pass il e o di e en empe a u e. Fig. 10 shows he simula ed equency esponses o he p oposed six h-o de Bu e wo h low-pass il e . The cu -o equency o he il e was 99 Hz and he DC ol age gain was -2.4 dB while he il e consumed 172 nW o powe . The simula ed equency esponse was also compa ed wi h heo e ical cu e. Fig. 11 shows he a ia ions o he equency esponse o empe a u e a ied om 0 o 75 °C. The simula ion esul shows ha he DC ol age gain a ied be ween -2.12 dB and -4.34 dB, whe eas he a ia ions o he cu - o equency o he il e we e negligible. Fig. 12 shows he simula ed ansien esponse o he il e when he 10 Hz sinusoidal inpu ol age signal wi h he ampli ude o 240 mV (peak- o-peak) was applied. This esul can be shown he ope a ion o inpu ol age swing o 240 mV (peak- o-peak) wi h he o al ha monic dis o ion (THD) o 1.09 %. To es he linea i y o he p oposed il e , a single one es and wo- one es ha e been in es iga ed. Fig. 13 shows he esul s o he single one es o he p oposed il e when he inpu equency o 10 Hz was supplied whe eas ampli ude o inpu sinusoidal ol age was a ied. The THD was 1.09 % when he ampli ude o inpu ol age was inc eased o 240 mV (peak- o-peak). The wo- one es has been in es iga ed by applying wo inpu equencies o 50 Hz and 60 Hz in o he ci cui and he ampli ude o inpu sinusoidal ol ages was a ied. The simula ed 3 d in e -modula ion dis o ion (IMD) was shown in Fig. 14. I can be ound ha ampli ude o he ou pu signal o a 2% 3 d IMD was 50 mV while he ampli ude o he inpu signal was 140 mV (peak- o-peak). 050 100 150 200 250 300 350 400 450 500 -160 -120 -80 -40 0 40 80 120 160 Time, ms Vol age, mV Vin Vou Fig. 12. Simula ed ansien esponse wi h inpu ol age swing. Fig. 13. THD a ia ion e sus ampli ude o he inpu sinusoidal ol age a 10 Hz . 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 050 100 150 200 250 300 THD, % Vin (peak- o-peak), mV Fig. 14 . The hi d-o de IMD e sus he inpu ol age. In case o noise es ing, he p oposed six h-o de Bu e wo h low-pass il e was simula ed o e alua e he in eg a ed inpu e e ence noise o he bandwid h o 100 Hz. F om ou simula ion, i can be ound ha an inpu - e e ed noise ol age was 338 µV ms whe eas an ou pu - e e ed noise ol age was 238 µV ms. I a single- one es has been used o de ine he dynamic ange (DR), a THD o 1.09 % (Vin = 84.8 mV ms), he DR was 48 dB. The p oposed six h-o de low-pass il e has been compa ed wi h p e ious wo ks [23], [24], [43]-[45] as shown in Table II. I can be shown ha he p oposed DDCC can be applied o biomedical sys ems because he ci cui can ope a e wi h ul a-low supply ol age and ul a- low powe consump ion. In o de o e alua e and compa e he pe o mance o he il e s in Table II, he ollowing s anda d Figu e o Me i (FoM) [46] was used 𝐹𝑜𝑀= 𝑃×𝑉𝐷𝐷 𝑁×𝑓𝑐×𝐷𝑅 (20) 0.0 0.5 1.0 1.5 2.0 2.5 25 50 75 100 125 150 3 d IMD, % Vin (peak- o-peak), mV Table II. Compa ison o he p oposed il e o some p e ious six h-o de low-pass il e s. This wo k 2000 [43] 2014 [44] 2019 [23] 2019 [24] 2019 [45] Technology [m] 0.18 0.8 0.35 0.13 0.18 20 Supply ol age [V] 0.3 ±1.5 0.5 0.25 1 10 Topology CMOS CMOS CMOS CMOS CMOS a-IGZO TFT Numbe o ac i e 6-DDCC 8-OTA 50-MOS 5-FDDTA, 1- OTA 6-OTA 3-DDA Numbe o passi e 9-R & 6-C 6-C 6-C 5-C 5-C 15-C, 24-MSW† Fil e o de 6 h LP (Bu e wo h) 6 h LP (Bu e wo h) 6 h LP (Bessel) 5 h LP (Bu e wo h) 5 h LP (Bu e wo h) 6 h LP (Bu e wo h) A chi ec u e Fully di . Single-ended Single-ended Fully di . Fully di . Fully di . Bandwid h [Hz] 99 2.4 2.4 100 250 272 Noise [V ms] 339 <50 0.43E-12 A* 4.7 134 - DC gain [dB] -2.5 -10 0 ~ -6 -7 -0.65 Powe consump ion [W] 172E-9 10E-6 7.21E-9 603E-9 41E-9 0.537E-3 Dynamic ange [dB] 48@1%THD [email p o ec ed]%THD 51.1@4%THD 57 61.2 - FOM 1.76E-12 3.47E-8 4.9E-12 5.29E-12 5.47E-13 - No e: * cu en -mode il e , † MSW = MOS swi ch, a-IGZO TFT = amo phous indium-gallium-zinc oxide (a-IGZO) hin- ilm ansis o (TFT) DDA = di e en ial di e ence ampli ie , R = esis o , C = capaci o FDDTA = ully di e en ial di e ence ansconduc ance ampli ie , OTA = ope a ional ansconduc ance ampli ie 5. Conclusion This pape p esen s a new di e en ial di e ence cu en con eyo (DDCC) wi h ul a-low ol age and low-powe capabili y o applica ion o biomedical sys ems. The DDCC is designed by using a non- ailed di e en ial pai wi h mul iple-inpu bulk-d i en MOS ansis o echnique o ob ain a ail- o- ail inpu common-mode ange and ex emely low supply ol age. The MOS ansis o s biased in he sub- h eshold egion ha e been used o achie e ul a-low powe consump ion. The p oposed DDCC is capable o ope a ing wi h a supply ol age as low as 0.3 V and consumes abou 28.6 nW o s a ic powe . The p oposed DDCC has been used o ealize a six h-o de Bu e wo h low-pass il e o applica ion o elec oca diog am sys ems as applica ion example. The pe o mance o he p oposed DDCC is e alua ed by simula ion esul s using SPICE p og am and MOS ansis o s pa ame e s p o ided by a s anda d n-well 0.18 µm CMOS p ocess om TSMC. Acknowledgmen This wo k was suppo ed by Facul y o Enginee ing, King Mongku ’s Ins i u e o Technology Ladk abang unde g an 2563-02-01-012. Resea ch desc ibed in his pape was inanced by he Na ional Sus ainabili y P og am unde g an LO1401. Fo he esea ch, in as uc u e o he SIX Cen e was used. Re e ences [1] S.–I. Liu, H.–W. Tsao, J. Wu, “CCII-based con inuous- ime il e s wi h educed gain- bandwid h sensi i i y,” IEE P oceedings G–Ci cui s, De ices and Sys ems, ol. 138, pp. 210–216, 1991. [2] A. De Ma cellis, C. Di Ca lo, G. Fe i, V. S o nelli, “A CCII‐based wide equency ange squa e wa e o m gene a o ,” In e na ional Jou nal o Ci cui Theo y and Applica ions, ol. 41, pp. 1–13, 2011. [3] T. Zuo, K. Sun, X. Ai, H. Wang, “High-O de G id Mul isc oll Chao ic A ac o s Gene a ed by he Second-Gene a ion Cu en Con eyo Ci cui ,” IEEE T ansac ions on Ci cui s and Sys ems-II: Exp ess B ie s, ol. 61, pp. 818–822, 2014. [4] P. Pawa angkoon, W. Ki anon, “Elec onically unable loa ing esis o ,” In e na ional Jou nal o Elec onics, ol. 91, pp. 665–673, 2004. [5] M. O. Cicekoglu, “Ac i e simula ion o g ounded induc o s wi h CCII+s and g ounded passi e elemen s,” In e na ional Jou nal o Elec onics, ol. 85, pp. 455–462, 1998. [6] C. Sanchez-Lopez, J. Mendoza-López, M. A. Ca asco-Aguila , C. Muñiz-Mon e o, “A Floa ing Analog Mem is o Emula o Ci cui ,” IEEE T ansac ions on Ci cui s and Sys ems-I: Exp ess B ie s, ol. 61, pp. 309-313, 2014. [7] M. Kumnge n, T. Non hapu ha, F. Kha eb, “Low powe sample and hold ci cui s using cu en con eyo analogue swi ches,” IET Ci cui s, De ices & Sys ems, ol. 12, pp. 397-402, 2018. [8] R. Senani, D. R. Bhaska , A. K. Singh, Cu en con eyo s: a ian s, applica ions and ha dwa e implemen a ions, Sp inge In e na ional Publishing Swi ze land, 2015 (pp. 3). [9] A. Sed a, K. C. Smi h, “A second-gene a ion cu en con eyo and i s applica ions,” EEE T ansac ions on Ci cui Theo y, ol. 17, ol. pp. 132–134, 1970. [10] W. Chiu, S. Liu, H. Tsao, J. Chaen, “CMOS di e en ial di e ence cu en con eyo and hei applica ions,” IEE P oceedings Ci cui s De ices Sys ems, ol. 143, pp. 91–96, Ap il 1996. [11] O. Elwan, A. M. Soliman, “No el CMOS di e en ial ol age cu en con eyo and i s applica ions,” IEE P oceedings–Ci cui s, De ices and Sys ems, ol. 144, pp. 195–200, 1997. [12] A. Zeki, A. Toke , “The dual-X cu en con eyo (DXCCII): a new ac i e de ice o unable con inuous- ime il e s,” In e na ional Jou nal o Elec onics, ol. 89, pp. 913– 923, 2003. [13] S. Maheshwa i, D. Ag awal, “Cascadable and unable analog building blocks using EX- CCCII,” Jou nal o Ci cui s, Sys ems and Compu e s, ol. 26 (1750093) 2017. [14] H. O. Elwan, A. M. Soliman, “CMOS di e en ial cu en con eyo s and applica ions o analog VLSI,” Analog In eg a ed Ci cui s and Signal P ocessing olume, pp. 35–45, 1996. [15] A. A. El–Adawy, A. M. Soliman, H. O. Elwan, “A no el ully di e en ial cu en con eyo and applica ions o analog VLSI,” IEEE T ansac ions on Ci cui s and Sys ems II: Analog and Digi al Signal P ocessing, ol. 47, pp. 306–313, 2000. [16] E. Sackinge , W. Guggenbuhl, “A e sa ile building block: The CMOS di e en ial di e ence ampli ie ,” IEEE Jou nal o Solid-S a e Ci cui s, ol. SC-22, pp. 287–294, 1987. [17] A. Yesil, Y. Babacan, F. Kaca , “A new DDCC based mem is o emula o ci cui and i s applica ions,” Mic oelec onics Jou nal, ol. 45, pp. 282–287, 2014. [18] C.–N. Lee, Independen ly unable plus– ype DDCC-based ol age-mode uni e sal biquad il e wi h MISO and SIMO ypes,” Mic oelec onics Jou nal, ol. 67, pp. 71– 81, 2017. [19] C.–M. Chang, S. –H. Tu, M. N. S. Swamy, A. M. Soliman, “Analy ical syn hesis o ellip ic ol age-mode e en/odd-n h-o de il e s uc u es using DDCCs, FDCCIIs, and g ounded capaci o s and esis o s,” IET Ci cui s, De ices and Sys ems, ol. 13, pp. 279–291, 2019. [20] A. Abaci, E. Yuce, “Single DDCC based new immi ance unc ion simula o s employing only g ounded passi e elemen s and hei applica ions,” Mic oelec onics Jou nal, ol. 83, pp. 94–103, 2019. [21] S. K. Mish a, M. Gup a, D. K. Upadhyay, “Design and implemen a ion o DDCC-based ac ional-o de oscilla o ,” In e na ional Jou nal o Elec onics, ol. 106, pp. 581–598, 2019. [22] R. Sa peshka , Ul a low powe bioelec onics, Fundamen als, biomedical applica ions, and bio-inspi ed sys ems, Camb idge Uni e si y P ess, 2010. [23] P. M. Pin o, L. H. C. Fe ei a, G. D. Colle a, R.A.S. B aga, “A 0.25-V i h-o de Bu e wo h low-pass il e based on ully di e en ial di e ence ansconduc ance ampli ie a chi ec u e,” Mic oelec onics Jou nal, ol. 92 (104606), 2019. [24] S.–Y. Lee, C.–P. Wang, Y.–S. Chu, “Low- ol age OTA–C il e wi h an a ea and powe -e icien OTA o biosignal senso applica ions,” IEEE T ansac ions on Biomedical Ci cui s and Sys ems, ol. 13, pp. 56–67, 2019. [25] C. Sawigun, S. Thanapi ak, “A nanopowe biopo en ial lowpass il e using sub h eshold cu en - euse biquads wi h bulk e ec sel -neu aliza ion,” IEEE T ansac ions on Ci cui s and Sys ems–I, ol. 66, pp. 1746–1752, 2019. [26] F. Ka ami Ho es ani, M. Eshghi, M. Yazdchi, “An ul a-low powe ampli ie o wea able and implan able elec onic de ices,” Mic oelec onic Enginee ing, ol. 216 (111054) 2019. [27] C. Psychalinos, S. Minaei, L. Sa a i, “Ul a low–powe elec onically unable cu en - mode ins umen a ion ampli ie o biomedical applica ions,” AEU–In e na ional Jou nal o Elec onics and Communica ions, ol. 117 (153120), 2020. [28] F. Kha eb, S. Vlassis, M. Kumnge n, C. Psychalinos, T. Kulej, R. V ba, L. Fujcik, “1 V ec i ie based on bulk-d i en quasi- loa ing-ga e di e en ial di e ence ampli ie s,” Ci cui s Sys ems and Signal P ocessing, ol. 34, pp. 2077–2089, 2014. [29] Y. Babacan, “Ul a-Low ol age-powe DTMOS based ull-wa e ec i ie ,” AEU– In e na ional Jou nal o Elec onics and Communica ions, ol. 91, pp. 18–23, 2018. [30] A. Namda i, M. Dola shahi, “A new ul a low-powe , uni e sal OTA-C il e in sub h eshold egion using bulk–d i e echnique,” AEU–In e na ional Jou nal o Elec onics and Communica ions, ol. 82, pp. 458–466, 2017 [31] H. Veldandi, R. A. Shaik, “A 0.3–V Pseudo–Di e en ial Bulk-Inpu OTA o Low– F equency Applica ions,” Ci cui s, Sys ems, and Signal P ocessing, ol. 37, pp. 5199– 5221, 2018. [32] T. Kulej, F. Kha eb, “A Compac 0.3-V Class AB Bulk-D i en OTA,” IEEE T ansac ions on Ve y La ge Scale In eg a ion (VLSI) Sys ems, pp. 28, pp. 224–232, 2020. [33] G. Raikos, S. Vlassis and C. Psychalinos, “0.5V bulk-d i en analog building blocks,” AEU–In e na ional Jou nal o Elec onics and Communica ions, ol. 66, 920–927, 2013. [34] F. Kha eb, T. Kulej, M. Kumnge n, “0.3V bulk-d i en cu en con eyo , IEEE Access, ol. 7, pp. 65122–65128, 2019. [35] F. Kha eb, T. Kulej, “Design and implemen a ion o a 0.3-V di e en ial di e ence ampli ie ,” IEEE T ansac ions on Ci cui s and Sys ems I: Regula Pape s, ol. 66, pp. 513-523, 2019. [36] F. Kha eb, W. Jaikla, M. Kumnge n, P. P ommee, “Compa a i e s udy o sub- ol di e en ial di e ence cu en con eyo s,” Mic oelec onics Jou nal, ol. 44, pp. 1278- 1284, 2013. [37] F. Kha eb, M. Kumnge n, S. Vlassis, C. Psychalinos, “Di e en ial di e ence cu en con eyo using bulk-d i en echnique o ul a-low- ol age applica ions,” Ci cui s Sys ems and Signal P ocessing, ol. 33, pp. 159-176, 2014. [38] F. Kha eb, “The expe imen al esul s o he bulk-d i en quasi- loa ing-ga e MOS T ansis o ,” AEU-In e na ional Jou nal o Elec onics and Communica ions, ol. 100, pp. 462-466, 2015. [39] F. Kha eb, T. Kulej, H. Veldandi, W. Jaikla, “Mul iple-inpu bulk-d i en quasi- loa ing- ga e MOS ansis o o low- ol age low-powe in eg a ed ci cui s,” AEU-In e na ional Jou nal o Elec onics and Communica ions, ol. 100, pp. 32-38, 2019. [40] F. Kha eb,T. Kulej, M. Kumnge n, W. Jaikla, R. K. Ranjan, “Compa a i e pe o mance s udy o mul iple-inpu bulk-d i en and mul iple-inpu bulk-d i en quasi- loa ing-ga e DDCCs,” AEU-In e na ional Jou nal o Elec onics and Communica ions, ol. 108, pp. 19-28, 2019. [41] M. Kumnge n, F. Kha eb, T. Kulej, “0.3 V di e en ial di e ence cu en con eyo using mul iple-inpu bulk-d i en echnique,” Ci cui s, Sys ems & Signal P ocessing, ol. 39, pp. 3189–3205, 2020. [42] T. Kulej, “0.5-V bulk-d i en CMOS ope a ional ampli ie ,” IET Ci cui s, De ices & Sys ems, ol. 7, pp. 352–360, 2013. [43] S. Solis-Bus os, J. Sil a-Ma inez, F. Malobe i, E. Sanchez-Sinencio, “A 60-dB dynamic- ange CMOS six h-o de 2.4-Hz low-pass il e o medical applica ions,” IEEE T ansac ions on Ci cui s and Sys ems-II: Analog and Digi al Signal P ocessing, ol. 47, pp. 1391–1398, 2000. [44] P. Be sias, C. Psychalinos, “Ul a-low ol age six h-o de low pass il e o sensing he T-wa e signal in ECGs,” Jou nal o Low Powe Elec onics and Applica ions, ol. 4, pp. 292-303, 2014.