0.3-V Nanopower Biopotential Low-Pass Filter

Recei ed June 12, 2020, accep ed June 26, 2020, da e o publica ion June 29, 2020, da e o cu en e sion July 9, 2020. Digi al Objec Iden i ie 10.1109/ACCESS.2020.3005715 0.3-V Nanopowe Biopo en ial Low-Pass Fil e TOMASZ KULEJ 1, FABIAN KHATEB 2,3, AND MONTREE KUMNGERN 4 1Depa men o Elec ical Enginee ing, Częs ochowa Uni e si y o Technology, 42-201 Częs ochowa, Poland 2Depa men o Mic oelec onics, B no Uni e si y o Technology, 60190 B no, Czech Republic 3Facul y o Biomedical Enginee ing, Czech Technical Uni e si y in P ague, 3105 Kladno, Czech Republic 4Depa 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 Co esponding au ho : Fabian Kha eb ([email p o ec ed].cz) This wo k was suppo ed by he King Mongku ’s Ins i u e o Technology Ladk abang unde G an KREF026201, and in pa by he Na ional Sus ainabili y P og am unde G an LO1401. ABSTRACT This pape p esen s a compac powe -e icien CMOS ou h-o de low-pass il e sui able o elec oca diog am (ECG) acquisi ion sys ems. The CMOS s uc u e o he p oposed il e u ilize he bulk- d i en echnique and ope a es in sub h eshold egion o achie e ex emely low- ol age supply (0.3V) and nanopowe consump ion (0.676 nW) o cu -o equency o 100 Hz. The il e was designed and simula ed using 0.18 µm CMOS TSMC echnology. The o al inpu e e ed noise o he il e is 87 µV ms and he dynamic ange is 58.1 dB. The il e o e s he bes igu e o me i o 2.91 ×10−14 J, he lowes powe consump ion and ol age supply, compa ed wi h he p e ious s a e-o - he-a nanowa il e designs. INDEX TERMS Biopo en ial il e , bulk-d i en, low ol age, low powe . I. INTRODUCTION In ecen yea s, an inc eased in e es in he design o ul a- low- ol age (ULV) and ul a-low-powe (ULP) elec onic sys ems, de o ed o biomedical applica ions, is obse ed. This new end is associa ed wi h he de elopmen o di e en kind o implan able and wea able biomedical sys ems, whe e low dissipa ion powe is o c ucial impo ance [1], [2]. One o he mos impo an blocks in such sys ems is he low-pass il e (LPF). As an example le us conside a ypical elec oca diog am (ECG) acquisi ion sys em shown in Fig.1. The weak ECG signal, whose ampli ude is in he ange o 100 µV- 4 mV is i s ampli ied by a low-noise p eampli ie wi h a iable gain, ypically in he ange o 10-100 V/V [1]. Nex i is il e ed wi h a LPF wi h adjus able cu o equency c(100-250 Hz), o dec ease ou - o -band noise. Finally, he signal is con e ed in o digi al o m by an analog- o-digi al con e e (ADC) [1], [2]. Ac i e il e s de o ed o such applica ions usually ha e e y simple s uc u es and exploi MOS ansis o s ope a ing in sub- h eshold egion. This allows dec easing bo h, he dis- sipa ion powe , as well as he occupied a ea. Simple s uc u e allows dec easing he inpu e e ed noise as well. In ecen yea s a numbe o ULV and ULP solu ions o biopo en ial il e s has been p oposed [3]–[7]. In o de o simpli y hei s uc u es, usually he au ho s use a single The associa e edi o coo dina ing he e iew o his manusc ip and app o ing i o publica ion was Dušan G ujić . FIGURE 1. ECG acquisi ion sys em. ansis o as a ansconduc o , o ealize a gm-C in eg a o . Thei linea i y and dynamic ange (DR) is usually imp o ed hanks o he local o global nega i e eedback loops. In o de o u he dec ease hei s uc u es and cu en consump ion, some o he p oposed solu ions o biquad a ic sec ions con- ain only one b anch o cu en , consis ing o se e al s acked ansis o s [4]–[6]. Howe e , he s acked ansis o s be ween he supply ails limi he minimum supply ol age (VDD) and en ail di e en dc le els be ween inpu and ou pu . In o de o o e come he abo e men ioned cons ain s and u he dec ease bo h, he supply ol age, as well as he dissipa ion powe (Pdiss) o an ECG il e , a bulk-d i en (BD) echnique can be conside ed. The BD ci cui s p o ed hei capabili y o ope a e om ex emely low VDD, e en much below he h eshold ol age (VTH) o MOS ansis o s, while main aining he inpu common mode ange (ICMR) almos ail- o- ail [7]–[13]. I is also wo h no ing, ha in some cases he BD app oach can ex end he DR o analog ci cui unde ULV supply, since i can ex end he inpu ange o which 119586 This wo k is licensed unde a C ea i e Commons A ibu ion 4.0 License. Fo mo e in o ma ion, see h ps://c ea i ecommons.o g/licenses/by/4.0/ VOLUME 8, 2020 T. Kulej e al.: 0.3-V Nanopowe Biopo en ial Low-Pass Fil e FIGURE 2. CMOS schema ic o he biquad il e (a) and i s block diag am (b). he ci cui pe o mance is no limi ed by ha d non-linea i ies. The e o e, he BD echnique can be a p omising app oach o design ULV ECG il e s. In his pape we p opose a new solu ion o an ULV ECG il e based on he BD app oach. The il e is a cascade connec ion o wo newly-p oposed ULV BD biquad il e s. Simila ly as in [4], he biquad was de eloped om a low- ol age cu en e-use CMOS bu e [14]. Ne e heless, since he adi ional long- ailed ga e-d i en (GD) di e en ial pai was eplaced wi h a non- ailed BD di e en ial pai , a much lowe minimum supply ol age was achie ed. The lowe VDD en ails lowe Pdiss o he o e all s uc u e. Mo eo e , he DR o he p oposed biquad is be e han epo ed o o he designs in li e a u e, e en hough i s supply ol age is much lowe (0.3 V). Due o he low dissipa ion powe and good DR, he p oposed il e ou pe o ms o he ECG il e s in e ms o s anda d Figu es o Me i (FOMs). The es o he pape is o ganized as ollows. In Sec ion II he newly-p oposed BD biquad il e is discussed in de ail. Sec ion III desc ibes he o e all s uc u e o he ECG il e . The simula ion esul s and compa ison wi h o he simila designs a e p esen ed in Sec ion IV. Finally, he pape is concluded in Sec ion V. II. PROPOSED BIQUAD CELL A. CIRCUIT DESCRIPTION The schema ic o he p oposed ULV biquad il e is shown in Fig. 2. I s p inciple o ope a ion is based on he idea o a simple CMOS uni y-gain bu e [14]. This idea has been nex adop ed o signal il e ing pu poses, in a simila way as desc ibed in [4]. The ci cui shown in Fig. 2. exploi s simila ope a ion p inciple, howe e , in his s uc u e a a- di ional long- ail GD di e en ial ampli ie has been eplaced by a non- ailed BD di e en ial ampli ie composed o he ansis o s M1A,B-M2A,B. Due o he non- ailed a chi ec u e combined wi h he BD app oach, a ail- o- ail inpu swing can be achie ed o e y low supply ol age. The inpu di e en ial ampli ie , composed o he ansis- o s M1A,B-M2A,B, exploi s he idea i s p oposed in [15]. Le us assume ha V1and V2 ep esen he inpu ol ages o he ampli ie and he connec ion be ween he biquad ou pu node and V2is b oken. The ansis o s M1A-M2A and M1B-M2B o m wo cu en mi o s, biased wi h he cu en sinks IB1 = IB2 =IB. The inpu signals a e applied o he bulk e minals o he ansis o s M1A,B-M2A,B, as shown in Fig. 2. Assuming V1=V2, he VBS ol ages o all ansis o s a e equal o each o he , which en ails ha hei h eshold ol ages a e equal as well. The e o e, neglec ing he impac o gds conduc ances, he cu en s I1and I2a e also equal o each o he and equal o IB. Consequen ly, o V1=V2, he di e en ial ou pu cu en o he i s s age (I1-I2) is equal o ze o, i.e. wi h he abo e assump ions, he inpu ampli ie is insensi i e o he common- mode ol age. Fo inpu di e en ial signals, when V16=V2, he h eshold ol ages o M1A and M2A (M1B and M2B) a e di e en , because o he dependence o he h eshold ol ages o MOS ansis o s on hei bulk po en ials. This a ec s he cu en ans e a io o he cu en mi o s and p oduces a di e ence o he ou pu cu en s I1and I2. Assuming ha he p-channel ansis o ope a es in sa u- a ed weak in e sion egion, i s ans e cha ac e is ics can be app oxima ed as: ID=IOW Lexp VSG +VTH npUT(1) whe e Iois he echnology cu en , npis he sub h eshold slope ac o o p-channel MOS and UTis he he mal po en- ial. The h eshold ol age VTH, can be exp essed as a unc- ion o VBS ol age as ollows: VTH =VTHO −γpp2|φF|+VBS −p2|φF|(2) whe e VTHO is he h eshold ol age o VBS =0, 2|8F| is wice he Fe mi po en ial and γpis he bulk h eshold pa ame e . S aigh o wa d analysis shows ha wi h he abo e model he di e en ial ou pu cu en o he i s s age I1-I2can be exp essed as: I1−I2= −2IBsinh ηV1−V2 npUT(3) VOLUME 8, 2020 119587 T. Kulej e al.: 0.3-V Nanopowe Biopo en ial Low-Pass Fil e whe e ηis he a io o he bulk (gmbp) o ga e (gmp) anscon- duc ance o he ansis o s M1A,B-M2A,Ba he ope a ing poin , gi en by: η=gmbp gmp =γp 2√2|φF|+VBS (4) As i can be concluded om he abo e conside a- ions, he ansis o s M1A,B-M2A,B o m a uly di e en- ial ( ansconduc ance) ampli ie , wi h non-linea la ge signal cha ac e is ic gi en by (3) and he small-signal ansconduc- ance which may be app oxima ed as [15]: gm≈2gmbp (5) I is wo h men ioning, ha bo h, i s noise p ope ies and o se a e no wo se han obse ed o he co esponding BD di e en ial pai biased wi h he same o al cu en [10], [15]. The ansis o M3B o m a second ansconduc ance s age. Consequen ly, he equi alen block diag am o he p oposed biquad may be p esen ed in he o m shown in Fig.2.b whe e gmn =gm3B. I is wo h poin ing ou , ha due o he non- ailed a chi- ec u e o he i s ansconduc o in Fig. 2, he minimum supply ol age o he p oposed biquad il e is as low as 2VDSsa , whe e VDSsa is he sa u a ion ol age o an MOS ansis o (3-4 UTin weak in e sion egion). The inpu /ou pu swing is limi ed by he ou pu cha ac e is ics o M1B and M3B. Because o he nega i e eedback loop, he maximum (minimum) ou pu ol age can be e y close o supply ails. B. TRANSFER FUNCTION The ans e unc ion o he biquad il e in Fig. 2b can be exp essed as ollows: Vou (s) Vin(s)= gmbpgmn C1C2 s2+sgmn C2+gmbpgmn C1C2 (6) hus, i is ansmi ance o a low-pass il e , whe e i s dc ol age gain (ADC), na u al equency (ωo), and quali y ac o (Q), a e espec i ely gi en by: ADC =1 (7) ωo= gmbpgmn C1C2 (8) Q=sgmbpC2 gmnC1 (9) Assuming gmn =IB/nnUTand gmbp =ηIB/npUT, he na u al equency and he quali y ac o may be exp essed in he o m: ωo=IB UTsη nnnpC1C2 (10) Q=sηnnC2 npC1 (11) As i is easy o no e, he na u al equency o he biquad il e is p opo ional o he biasing cu en IBand can be easily TABLE 1. T ansis o s aspec a ios and il e capaci ances. uned wi h his cu en . On he o he hand, a ia ions o IB will no a ec he quali y ac o Q. Bo h quan i ies (ωoand Q) will depend sligh ly on he p ocess, supply ol age and empe a u e (PVT) a ia ions, because he PVT a ia ions will a ec he slope ac o s nn, np, he coe icien ηand UT. Howe e , one can expec ha he a ia ions will be on accep able le el. The uning ange o ωois limi ed by he accep able ange o |VGS/VDS| ol age d ops ac oss MOS ansis o s in his ci cui , ha p o ide ope a ion o all ansis o s in sa u a ion. C. NOISE PERFORMANCE The he mal 2 ,and licke 2 1/ ,noise spec al densi ies o a MOS ansis o can be exp essed as ollows: 2 =8kT 3gm (12) 2 1/ =Kg2 m CoxWL (13) whe e k is he Bol zmann cons an , T is he absolu e em- pe a u e, gmis he ansconduc ance, Cox is he ga e oxide capaci ance pe uni a ea and K is he licke noise cons an . Assuming he abo e noise model, and neglec ing he sec- ond o de e ec s, he low equency (  c) inpu e e ed noise o he conside ed biquad in a weak in e sion egion can be exp essed as: 2 b =28kT 3ηgmbp 1+np nn(14) 2 1/ b =2 Coxη2"Kp WL1,2+Kn WL3,5np nn2#(15) Usually, he he mal noise will be dominan , because o e y low biasing cu en s ( ansconduc ances) and ela i ely la ge sizes o MOS ansis o s, equi ed in ULV en i onmen . No e, ha he noise pe o mance o he biquad il e will be de e io a ed by he BD app oach (η1), which is a well known disad an age o all BD ci cui s. III. BIOPOTENTIAL FILTER The biopo en ial il e can be ealized as a cascade connec ion o wo biquad il e s desc ibed in he p e ious sec ion. I s ansis o -le el schema ic is shown in Fig. 3. T ansis o MB is used o biasing pu poses. No e, ha ansis o sizes and biasing cu en s in bo h sec ions we e assumed o be iden ical. 119588 VOLUME 8, 2020 T. Kulej e al.: 0.3-V Nanopowe Biopo en ial Low-Pass Fil e FIGURE 3. CMOS schema ic o he p oposed biopo en ial il e . FIGURE 4. AC esponse o he il e o IB =0.25nA, c =100Hz. In o de o ob ain a ou h o de maximally la cha ac e is- ic wi h 3-dB equency o 100-Hz, o he assumed IB= 0.25 nA (gmbp =2.63 nS gmn =7.0 nS), he used capac- i ances we e calcula ed as shown in Table 1. This esul s in o/Q equal o 99.3 Hz/0.87 o he i s and 129 Hz/0.65 o he second sec ion o he il e espec i ely. The channel leng hs o all ansis o s we e chosen el- a i ely la ge o maximize hei gm/gds a ios (in insic ol age gains). On he o he hand, hei channel wid hs we e ine uned du ing he simula ion phase o achie e |VGS| ≈VDD/2 a he ope a ing poin , ha p o ides maximum ol age head oom o possible PVT a ia ions and signal swing in an ULV en i onmen . The ansis o aspec a ios o he design a e also p o ided in Table 1. IV. SIMULATED RESULTS A. MAIN CHARACTERISTICS The ci cui has been implemen ed in a 0.18 µm CMOS p ocess om TSMC, wi h h eshold ol ages o a ound +/− 0.5 V. I s pe o mance was alida ed using Cadence/Spec e pla o m. The assumed supply ol age was 0.3 V (+/−0.15 V o he pu pose o simula ions). Fig. 4 shows he magni ude cha ac e is ic o he il e o IB=0.25 nA. The cha ac e is ic ag ee well wi h heo y. The dc ol age gain was 0.144 dB, while he cu o equency was FIGURE 5. AC esponse o he il e o (IB =0.25nA, c =100Hz), (IB = 0.377nA, c =150Hz), (IB =0.634nA, c =200Hz). FIGURE 6. F equency c e sus bias cu en IB. exac ly 100 Hz. The a enua ion in he s op band exceeded 60 dB, which is su icien o he conside ed applica ion. Fig. 5 shows a ia ions o he magni ude cha ac e is ic wi h he biasing cu en IB. Fo IB anging om 0.25 nA o 0.634 nA, he 3-dB equency ( c) o he il e is uned om 100 Hz o 250 Hz. No e, ha a ia ions o he dc ol age gain and shape o he cha ac e is ic (quali y ac o s o bo h sec ions) a e negligible, ha ag ees well wi h heo y. Fig. 6. shows he cu o equency o he il e agains he biasing cu en IB. As i is seen, he 3-dB equency can be linea ly uned o IB anging om 0.15 nA o 0.65nA, which VOLUME 8, 2020 119589 T. Kulej e al.: 0.3-V Nanopowe Biopo en ial Low-Pass Fil e TABLE 2. E ec o PVT a ia ion on he cu o equency. FIGURE 7. DC ans e cha ac e is ic o he il e showing ail- o- ail ol age ange. FIGURE 8. T ansien esponse o he il e o inpu sine wa e wi h Vinpp =200mV and 10 Hz. THD =1%. co esponds o c anging om 60 Hz o 260 Hz. This linea ange is limi ed by he |VGS/VDS| ol age d ops ac oss MOS ansis o s and can be ex ended o la ge VDD. Fig. 7 shows he s a ic ans e cha ac e is ic o he il e . I is wo h poin ing ou a e y good linea i y o his cha ac e - is ic, o nea ly ail- o- ail ol age swing. The la ge ol age swing in an ULV en i onmen is ob ained hanks o he BD app oach applied in his design. The good linea i y o he il e is con i med also by i s sine wa e esponse shown in Fig. 8. Fo he sine wa e o 200 mVpp and 10-Hz equency, he o al ha monic dis o ion (THD) was 1 %. The phase shi be ween inpu and ou pu signals in Fig.8 is caused by he phase cha ac e is ic o he il e . The abili y o he p oposed il e o a enua e noise is shown in Fig. 9. In Fig. 9a we can see an inpu ECG signal wi h an ampli ude o 50 mVp, in e e ed wi h a pa asi ic noise modeled as a 500-Hz sinusoidal signal wi h ampli ude FIGURE 9. T ansien esponse o he il e o noisy ECG signal, (a) inpu , (b) ou pu . o 5mVp. Fig. 9b shows he esul ing signal a he ou pu o he il e , which con i ms i s p ope ope a ion in his case. B. IMPACT OF PVT VARIATIONS AND MISMATCH In o de o in es iga e he il e sensi i i y o PVT a ia ions and ansis o misma ch, bo h, he co ne analysis as well as he Mon e Ca lo (MC) analysis ha e been pe o med. The esul s o co ne analysis a e shown in Table 2, whe e he impac o PVT a ia ions on he cu o equency o he il e a e shown and in Table 3, whe e i s dc gain is examined. Bo h pa ame e s show ela i ely low a ia ions unde he assumed ange o PVT a ia ions. The impac o ansis o misma ch on cand dc gain o he il e is shown in Figs. 10 and 11 espec i ely. The igu es show his og ams, being he esul s o MC analysis (200 uns). The obse ed s anda d de ia ions o c(3.19 Hz) and dc gain (0.034 dB) p o e a ela i ely low sensi i i y o he il e o ansis o misma ch. The inpu e e ed o se o he il e a ied om −2.9 mV o 1.8 mV, as a esul o PVT a ia ions, while he MC 119590 VOLUME 8, 2020 T. Kulej e al.: 0.3-V Nanopowe Biopo en ial Low-Pass Fil e TABLE 3. E ec o PVT a ia ion on he DC gain. TABLE 4. Pe o mance compa ison o nanopowe 4 h-o de LP il e s. FIGURE 10. The his og am o he equency c wi h 200 MC uns. misma ch analysis showed a mean alue o −0.291 mV and s anda d de ia ion o 4.91 mV. The abo e esul s show, ha he il e is obus unde PVT a ia ions and ansis o misma ch. No e, ha he impac o ansis o misma ch could be u he lowe ed, applying la ge ansis o channel sizes, a he cos o silicon a ea o he il e . C. COMPARISON Table 4 p esen s a compa ison o he p oposed il e wi h o he simila designs o biopo en ial il e s, published in FIGURE 11. The his og am o he DC gain wi h 200 MC uns. ecen yea s. Fi s o all is wo h no ing, ha he p oposed il e can ope a e wi h much lowe VDD han o he il e s in Table 4, excep [16]. Despi e i s single-ended a chi ec u e and ULV supply, he il e o e s he bes dynamic ange among all he compa ed il e s. This p ope y is achie ed hanks o he non- ailed BD a chi ec u es o he main blocks used in his design. No e, ha he DR could be u he imp o ed wi h a ully-di e en ial e sion o he p oposed ci cui . In o de o acili a e he compa ison, he ollowing VOLUME 8, 2020 119591 T. Kulej e al.: 0.3-V Nanopowe Biopo en ial Low-Pass Fil e FIGURE 12. Compa ison o FOMs and supply ol ages. s anda d FOM has been used: FOM =Pdiss N cDR (16) whe e N is he il e o de and he o he symbols we e de ined ea lie . As i can be concluded om (16), he abo e FOM akes in o accoun he powe e ec i eness o he il e , and e e s i o he achie ed DR. Lowe alue o his FOM means be e pe o mance o he il e . The alues o he calcula ed FOMs a e shown in Table 4 and in a g aphical o m in Fig. 12. As i is easy o no e, he p o- posed il e o e s he bes FOM, which is app oxima ely one o de o magni ude be e han achie ed o he design in [16], which was supplied wi h he same VDD. The mos simila FOM was epo ed o he il e in [5], howe e , ha ci cui was supplied wi h much la ge VDD. V. CONCLUSION A new design o an ULV, ou h-o de , biopo en ial (ECG) il e was p esen ed. The il e is a cascade connec ion o wo newly-p oposed second-o de (biquad) il e s, de eloped om a compac cu en e-use CMOS bu e s [4], [14]. Thanks o he applica ion o BD non- ailed di e en ial pai s, ins ead o adi ional ga e-d i en pai s, a new ULV biquad il e was ob ained, wi h e y low supply ol age (0.3 V) and ail- o- ail inpu /ou pu ange. The simula ed esul s showed, ha he ci cui ou pe o ms all o he designs in e ms o s anda d FOMs, and ope a es well also in he p esence o PVT a ia ions and ansis o misma ch. The il e pe o mance can be u he imp o ed wi h a ully-di e en ial e sion o his design. ACKNOWLEDGMENT Fo he esea ch, in as uc u e o he SIX Cen e was used. REFERENCES [1] S.-Y. Lee and C.-J. Cheng, ‘‘Sys ema ic design and modeling o a OTA- C il e o po able ECG de ec ion,’’ IEEE T ans. Biomed. 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TOMASZ KULEJ ecei ed he M.Sc. and Ph.D. deg ees (Hons.) om he Gdańsk Uni e si y o Technology, Gdańsk, Poland, in 1990 and 1996, espec i ely. He was a Senio Design Analysis Enginee wi h he Polish B anch, Chipwo ks Inc., O awa, ON, Canada. He is cu en ly an Associa e P o esso wi h he Depa men o Elec ical Engi- nee ing, Częs ochowa Uni e si y o Technology, Poland, whe e he conduc s lec u es on elec onics undamen als, analog ci cui s, and compu e aided design. He has au ho ed o coau ho ed o e 70 publica ions in pee - e iewed jou nals and con e ences. He holds h ee pa en s. His ecen esea ch in e - es s include analog in eg a ed ci cui s in CMOS echnology, wi h emphasis o low- ol age and low-powe solu ions. He se es as an Associa e Edi o o Ci cui s, Sys ems, and Signal P ocessing and IET Ci cui s, De ices and Sys ems. He se ed as a Gues Edi o o he Special Issues on Low Vol age In eg a ed Ci cui s on Ci cui s, Sys ems, and Signal P ocessing (2017), IET Ci cui s De ices and Sys ems (2018), and Mic oelec onics Jou nal (2019). 119592 VOLUME 8, 2020 T. Kulej e al.: 0.3-V Nanopowe Biopo en ial Low-Pass Fil e FABIAN KHATEB ecei ed he M.Sc. and Ph.D. deg ees in elec ical enginee ing and communi- ca ion and business and managemen om he B no Uni e si y o Technology, Czech Repub- lic, in 2002, 2003, 2005, and 2007, espec i ely. He is cu en ly a P o esso wi h he Depa men o Mic oelec onics, Facul y o Elec ical Engi- nee ing and Communica ion, B no Uni e si y o Technology. He is also wi h he Depa men o In o ma ion and Communica ion Technology in Medicine, Facul y o Biomedical Enginee ing, Czech Technical Uni e si y in P ague. He holds i e pa en s. He has au ho ed o coau ho ed o e 100 publica ions in jou nals and p oceedings o in e na ional con e ences. He has expe ise in new p inciples o designing low- ol age low-powe analog ci cui s, pa icula ly biomedical applica ions. He is a membe o he Edi o ial Boa d o Mic oelec onics Jou nal. He se es as an Associa e Edi o o Ci cui s, Sys ems and Signal P ocessing,IET Ci cui s, De ices and Sys ems, and he In e na ional Jou nal o Elec onics. He was a Gues Edi o o he Special Issue on Cu en -Mode Ci cui s and Sys ems, Recen Ad ances, Design and Applica ions on In e na ional Jou nal o Elec onics and Communica ions (2017). He was also a Lead Gues Edi o o he Special Issues on Low Vol age In eg a ed Ci cui s and Sys ems on Ci cui s, Sys ems, and Signal P ocessing (2017), IET Ci cui s, De ices and Sys ems (2018), and Mic oelec onics Jou nal (2019). MONTREE KUMNGERN ecei ed he B.S.Ind.Ed. deg ee in elec ical enginee ing om he King Mongku ’s Uni e si y o Technology Thonbu i, Thailand, in 1998, and he M.Eng. and D.Eng. deg ees in elec ical enginee ing om he King Mongku ’s Ins i u e o Technology Ladk abang, Thailand, in 2002 and 2006, espec i ely. F om 2007, he se ed as a Lec u e wi h he Depa men o Telecommunica ions Enginee ing, Facul y o Enginee ing, King Mongku ’s Ins i u e o Technol- ogy Ladk abang. F om 2010 o 2017, he se ed as an Assis an P o esso and he is cu en ly an Associa e P o esso . He has au ho ed o coau ho ed o e 200 publica ions in jou nals and p oceedings o in e na ional con e ences. His esea ch in e es s include analog and digi al in eg a ed ci cui s, disc e e- ime analog il e s, non-linea ci cui s, da a con e e s, and ul a-low ol age building blocks o biomedical applica ions. VOLUME 8, 2020 119593