MOS ANANLO INTERATED FILTERS. 7. 5. JOONHO HOI Department of Electrcal Engeerg Unversty of Seoul jcho@ee.uos.ac.kr
OUTLINE Introducton to Analog Integrated Flters Introducton to Transconductance (m)- Flters Transconductance rcuts Hgh-Order m- Flters Desgn Issues for m- Flters Desgn Examples Introducton to Swtched-apactor (S) Flters Swtched-apactor Integrators Hgh-Order S Flters Desgn Issues for S Flters Desgn Examples Smulaton Exercses
Introducton
Mxed-Sgnal Systems Pre-Amp Rx-Flter Analog Meda A A AD DA DSP & MU Dgtal Data Drver Tx-Flter AFE Performance Performance Requrements Requrements Pre-Amp Rx-Flter AFE AFE < AFE AFE AD D Analog Meda DA D DSP & MU Dgtal Data Drver AFE Tx-Flter
Analog Integrated Flters Analog Flters vs Dgtal Flters :-) Speed, Power Dsspaton, Slcon Area :-( Dynamc Range, Programmablty, ontrollablty ontuous-tme Flters m- Flter, MOSFET- Flter, Actve R- Flter, No Pre- & Post- Processg Requred Tung rcuts Requred Dscrete-Tme Flters Swtched-apactor (S) Flter, Swtched-urrent Flter Pre- & Post- Processg Requred Desrably Accurate
Flter Frequency Response Magntude haracterstcs H(f) A S A P f Phase haracterstcs f S f P f P f S Operatg Types Lowpass, Hghpass, Bandpass, Bandreject, Allpass Frequency Transformaton from LPF Prototype Response Types Butterworth, hebyshev (I,II), Ellptc, Equrpple
Hgh- Order Flter Implementaton ascadg of Bquad Blocks X(z) H (z)... H (z)... H N/ (z) Y(z) H(z) H (z)...h (z)...h N/ (z) H N ( z ) H ( z ) N b a z a z b z z b a Easy Adjustment of Frequency haracterstcs Pole/Zero Par Matchg Bquad Permutaton a Dstrbuton
Hgh- Order Flter Implementaton RL Prototype X(s) R S I L L 4 V V 3 I I 4 3 R L Y(s) I 4 I I V V 3 ( X V ) R S ( I I ) s ( V V 3 ) sl ( I I ) s 4 3 ( V I R ) sl 3 4 L Implemented wth Many Integrators Less Senstve to Varatons of omponents Easy to Obta Frequency Transformaton Impedance Transformaton
ontuous- Tme Flter Response H(s) X(s) Y(s) b a s s M N b a s s M N L L b a M N s b s a M N 5 H(f) [db] - -4-6 -8 - - 4 6 8 f [Hz] magary f [MHz] 4 3 - - -3-4 -5 -.5.5 real f [MHz]
Dscrete- Tme Flter Response H ( z) N D M M- ( z) b z b z L b z b M M N ( z) a z a z N- L a z a M M H( ω) [db] - -4-6 -8 - magary ω.8.6.4. -. -.4 -.6 -.8 -.p.4p.6p.8p p ω - - -.5.5 real ω
ontuous-tme Flter (m- Flter)
m Amplfer Bascs Transconductance (m) Amplfer v v - - m v v - - m - Sgle-Ended Fully-Dfferental Transconductance Amplfer haracterstcs Learty I/O Impedances v Operatg (Dynamc) Range Frequency haracterstcs Electrcally Programmable m Value R m, R m ( v v )
m Amp rcut Examples Smple Dfferental Par Example v M M v x v - β β ( v v V ) ( v v V ) x x TH TH I SS I SS β v ISS β v o - I SS for large I SS, small β & v m v v -v - βi SS β m I SS v -I SS
Dfferental Par w/ Degenerate Resstor Example - v M M v V R R I B I B R R I B R IB M R v v gs R R R v gs { v ( v v )} v gs gs for large β and small - ( V β) ( V β) β( ) v v gs gs TH TH m v v R
Dfferental Par w/ Degenerate Resstor & Feedback Example V DD I B I B M 5 M 6 v M M v - I B - o V I B o M 9 o M 7 M 3 M 4 M 8 I B I B V SS Negatve feedback loops (M -M 5 -M 3 & M -M 6 -M 4 ) forces constant currents I B to flow through M and M v gs v gs
T Amp usg MOS Saturaton urrent Saturaton MOSFET ds β ( v V ) gs TH Basc Prcple A B ( A B) ( A B) k ( v v ) omposte Transstor I D β eq ( V V ) Seq THeq M M v v V Seq - M n M p I D V V β Seq THeq eq V V SN THN N P ( β β ) N V β V SP β THP P M - 3 M 4 β eq - V FV V FV [ V V ] ( v v ) FV THeq
T Amp usg MOS Lear urrent Saturaton MOSFET ds β ( v V ) v v gs TH ds ds Basc Prcple ( A ) ( B ) A B v v Example p m p m ( ) ( ) ( ) ( ) 3 4 4 3 V 3 4 M M M V 3 M 4 A V A M A V A V 4 B β ( V V V )( V V ) ( V V ) B B TH B B B B I BIAS V B V B M B V B I BIAS 3 A β ( V V V )( V V ) ( V V ) A A TH A A A A V SS
m- Integrator KL H(ω) v v - - m v -6dB/dec ω unty db ω H(s) ω unty v v m m s <H(ω) o ω crtcal crtcal parameters parameters to to determe determe flter flter frequency frequency characterstcs characterstcs -9 o
st - Order m- Flter X m - V (s) - m A KL V (s) ( ) H s V V X s ( s) A X A X k s k ( s) s ω s A m X m m m X k ω k k ( ) A X ( ) A A X
nd - Order m- Flter (Bquad) KL V (s) - m4 A A m - - m B m3 - V (s) X B KL - m5 ( ) H s V V ( s) ( s) B X m 5 s s X B X A m 3 m s s B X A B ( ) ( ) m m B X m 4 X k s s k s k ω s ω Q
haracterstc Functon Flterg Operatons Lowpass k k Hghpass k k Bandpass k k s Q s r denomato ω ω ( ) X B A m m ω A X B m 3 m m Q ( ) X B A m 4 m X B m 5 X B X k k k
Hgh- Order m- Flter w/ Bquads 6th-order Ellptc BPF Passband : 48kHz~5kHz Passband Rpple : <.5dB Stopband Attenuaton : > 8dB - -4-6 -8-4 5 6 7 H (s) m m 7.6µ, m3.8µ m4 4.8µ, m5 µ A B 5p, X.39p H (s) m m 6.9µ, m3.5µ m4.µ, m5 µ A B 5p, X.39p H 3 (s) m m 4.89µ, m3.67µ m4 µ, m5.89µ A B 5p, X p
Hgh- Order m- Flter from RL R S L L 4 X(s) V V 3 Y(s) X(s) I V V 3 I I 4 3 R L Y(s) - - - t A S - t - t 3 t 4 V V V 4 I 4 I I V V 3 ( X V ) R V A ( X V ) S S ( I I ) s V ( V V ) sτ ( V ) V3 sl V ( ) V V3 sτ ( I ) I4 s ( ) 3 V 3 V V4 sτ ( V ) 3 I 4R L sl ( ) V 4 V 3 Y sτ4 3 Frequency Transformaton & Impedance Transformaton Requred
Non- Idealtes Fte Output Resstance ( ) H s R m sr Fte D a : BPF, HPF Reduced Phase (>-9 o ): Q decreases ascode Output Stage & ompensaton Technque Fte Parastc Pole Frequency ( ) H s m R sr s p t ernal Increased Phase (<-9 o ): Q creases areful Desgn Input apactance Loadg Frequency hange ( ) H s s m ( ) put Dummy ells
Learty Problems Nonlearty I 3 ( t) a V ( t) a [ V ( t) ] a [ V ( t) ] L 3 Harmonc Dstorton ( t) A s ( ω t) V ( t) I s ( ω t) I s ( ω t) I s ( 3ω t) L I 3 THD [db] I I I L 3 4 log I Inter Modulaton Dstorton V ( t) A[ s ( ω t) s ( ω t) ], ω ω IMD ω ω, ω -ω IMD3 ω ω, ω ω, ω -ω, ω -ω,
Dynamc Range Performance IIP3 : Input-Referred Thrd-Order Intercept Pot IP db : Input-Referred -db ompresson Pot SFDR : Spurous-Free Dynamc Range V OUT [dbm] db Fundamental IIP3 V IN [dbm] SFDR IP db N O IMD3
m Varatons Values of m mght change due to process varaton, temperature, agg,. Notch Flter - - -3 TT : SS : FF : freq. freq. change change Q change change [db] -4-5 -6 5 6 7 8 9 Freq. [MHz] Trmmg after chp fabrcaton possble, but one-tme event.
On- hp Tung Example for Bquad H (s ) s D (s ) ω s Q ω V IN phase comparator LPF V ωo ω REF PLL w ω O VO flter H(s ; ω O,Q) ampltude comparator LPF V Q V REF MLL Q V O Q reference ckt. V OUT
Recent Advance Example 55 Mbps Equalzer for Magnetc Storage Read hannels. mm 4-pole & -zero Equalzaton for Peak-Detect Scheme.8 mm.-µm MOS Technology SNR > 57 db, THD < % Power 4 mw ULA ( IEEE JSS, 994)
Recent Advance Example 7-th Order Equrpple m- Flter.4-µm MOS Technology f cutoff 5 MHz THD < %, Power mw (3 V) Htach ( IEEE ISS, 997)
Recent Advance Example 3 Rased-ose Matched Flter for 48 MHz QPSK Demodulator for DBS Analog Devces ( IEEE ISS, 997)
Recent Advance Example 4 6th-order BPF for J-PD x 8th-order BPF Average of f o : 45.5kHz σ of f o :.5kHz Tung Range of f o : 4~77kHz.35-µm MOS Power : 4.8mA @.5V Actve Area :.5mm Fujtsu ( IEEE ISS, 999)
Recent Advance Example 5 7th-order Equrpple roup Delay LPF 3 x Bquads f 3dB : 45.5kHz f 3dB Accuracy: % roup Delay Acc. : 5%.5-µm MOS Power Supply :.5V hp Area : 3mm Texas Instruments ( IEEE ISS, 999)