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Willy Sansen 10-05 071 Important opamp configurations Willy Sansen KULeuven, ESAT-MICAS Leuven, Belgium [email protected]
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Page 1: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 071

Important opamp configurations

Willy Sansen

KULeuven, ESAT-MICASLeuven, Belgium

[email protected]

Page 2: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 072

Table of contents

• Simple CMOS OTA• CMOS Miller OTA• Symmetrical CMOS OTA• Folded cascode OTA• Other opamps

Page 3: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 073

Simple CMOS OTA

12

3

VDD

VSS

vOUT

CL

M1 M2

M3 M4

M5

+ -

Cn2

GBW = gm12π CL

fnd = gm32π Cn2

Cn2= 2CGS3+CDB3+CDB1 ≈ 4CGS3

fnd ≈ ?fT3

4

Differential pairCurrent mirror

Page 4: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 074

Simple CMOS OTA : fnd

12

3

vOUT

M1 M2

M3 M4

M5

+ -

Cn2fnd =

gm3

2π Cn2

-90o

0o

Av

f

f

fnd 2fnd

2x

PM = 90o - arctan + arctan ≈ 85oGBWfnd

GBW2 fnd

2x

Page 5: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 075

Telescopic CMOS OTA

M1 M2

M3 M4

M9

+ - More gainAt low frequencies

GBW = 2π CL

gm1

vOUT

CL

M5 M6

M7 M8

Gulati, JSSC Dec.98, 2010-2019

Page 6: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 076

Cascodes increase gain at low frequencies

GBW = 2π CL

gm1

Av

GBW

f

Cascodes : high gain at low frequencies

No cascodes

104

102

1

Page 7: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 077

Table of contents

• Simple CMOS OTA• CMOS Miller OTA• Symmetrical CMOS OTA• Folded cascode OTA• Other opamps

Page 8: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 078

Miller CMOS OTA

12

34

VDD

VSS

vOUT

CLM1 M2

M3 M4

M5

M6

M7

+- Cc

GBW = gm12π Cc

fnd = gm62π CL

1

1 +Cc

Cn1

Differential pairCurrent mirrorSecond stage

Page 9: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 079

Miller BiCMOS OTA

12

34

VDD

VSS

vOUT

CLM1 M2

M3 M4

M5

M6

M7

+- Cc

M8 M9

56

Node 1:High impedance

Extra nodes 5, 6

gm6NPN > gm6NMOS

fnd ?

Page 10: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0710

Table of contents

• Simple CMOS OTA• CMOS Miller OTA• Symmetrical CMOS OTA• Folded cascode OTA• Other opamps

Page 11: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0711

Symmetrical CMOS OTA

12

345

VDD

VSS

vOUT

CLM1 M2

M3 M4

M8

M6

M7

+-

M5

M9

1 : BB : 1

B ?

Symmetrical :Node 1 = Node 2

Rail-to-rail output swing

Differential pair3 Current mirrors

1 : : 1

Page 12: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0712

Symmetrical CMOS OTA : GBW

12

345

VDD

VSS

vOUT

CLM1 M2

M3 M4

M8

M6

M7

+-

M5

M9

1 : BB : 1

B ?

Av = gm1BRn4

BW =1

2π Rn4CL

GBW = Bgm1

2π CL

1 : 1 =

if L8 > L6

2VEnL6

VGS1-VT

Page 13: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0713

Symmetrical CMOS OTA : fnd1,2

12

345

VDD

VSS

vOUT

CLM1 M2

M3 M4

M8

M6

M7

+-

M5

M9

1 : BB : 1

GBW = Bgm1

2π CL

Cn2 Cn1

Cn1= (1+B)CGS4+CDB4+CDB2

≈ (3+B)CGS4

fnd = gm42π Cn1

fT43+B

1 : 1

Page 14: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0714

Pole at output of a differential pair

M1 M2

+-

M9

Cn

RL

One single pole : fp = 12π 2RLCn

+ -voRL

M1 M2

+-

M9

2Cn RL

+ -voRL2Cn

Page 15: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0715

Symmetrical CMOS OTA : fnd5

12

345

VDD

VSS

vOUT

CLM1 M2

M3 M4

M8

M6

M7

+-

M5

M9

1 : BB : 1

GBW = Bgm1

2π CLCn5

Cn5 causespole

and zeroat 2 x freq.:≈ 3 …6 o

1 : 1

Page 16: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0716

VGS-VT = 0.5 V; L = 1 µmfT4 = 5 GHzfnd = 0.6 GHzB ≈ 5

Symmetrical CMOS OTA : Design Example

12

345 vOUT

CL = 2 pFM1 M2

M3 M4

M8

M6

M7

+-

M5

M9

1 : BB : 1

GBW = Bgm1

2π CL

fnd ≈fT4

3+B

GBW = 200 MHz

1 : 1

Page 17: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0717

12

345 vOUT

CM1 M2

M3 M4

M8

M6

M7

+-

M5

M9

1 : BB : 1

GBW = Bgm1

2π CL

fnd ≈fT4

3+B

gm4NPN > gm4NMOSCCS4NPN > CDB4NMOS

BiCMOS > CMOS ?

1 : 1

Symmetrical BiCMOS OTA

Page 18: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0718

Symmetrical CMOS OTA with cascodes

12

3 4

5

VDD

VSS

vOUTCLM1 M2

M3 M4

M8

M6

M7

+-

M5

M9

1 : BB : 1

GBW = Bgm1

2π CL

GBW samebut

Av is 100* xhigher !!!

* gmro ≈ 100

+

++

1 : 1

M9M10

M11 M12

Page 19: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0719

Symmetrical Miller CMOS OTA

12

345

VDD

VSS

vOUTCcM1 M2

M3 M4

M8

M6

M7

+-

M5

M9 M12

M10M9

M11

CL

67

8

GBW = Bgm1

2π CcNo zero !

B : 1 1 : B

1 : : 1

Page 20: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0720

Bipolar transistor symmetrical amplifier

CA3080

0.12 MHz1.2 V/µs

I3 = 10 µA

Page 21: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0721

Gain enhancement by current starving

inp inn

outnoutn

2I1

M1

M2M3

K*I1 1:B

kA

VVkA

TGS −=

⋅−−=

1))(1(2 0

31 λ

Yao, ..., JSSC Nov.04, 1809-1818

Page 22: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0722

Table of contents

• Simple CMOS OTA• CMOS Miller OTA• Symmetrical CMOS OTA• Folded cascode OTA• Other opamps

Page 23: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0723

Folded cascode CMOS OTA

VDD

VSS

vOUT

M1 M2

M3 M4

+-

M9 M6

M10 M11

CL

+

M7

M5

M8

6

35

4

2 1

7 Differential pairCascode pair2 Current mirrors

SymmetricalNode 1 = Node 2High speedInput to rail

Page 24: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0724

Folded cascode CMOS OTA : DC

VDD

VSS

vOUT

M1+-

M9

CL

+

3

2 1

10050 50

100 100

5050

M2

5050

DC current flow

M4

M11

Page 25: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0725

Folded cascode CMOS OTA :

VDD

VSS

vOUT

M1 M2

M3 M4

+-

M9 M6

M10 M11

CL+

M7

M5

M8

6

35

4

2 1

7

Av = gm1Rn4

BW = 12π Rn4CL

GBW = gm1

2π CL

Single stage ?

Page 26: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0726

Folded cascode CMOS OTA :

VDD

VSS

vOUT

M1 M2

M3 M4

+-

M9 M6

M10 M11

CL+

M7

M5

M8

6

35

4

2 1

7GBW =

gm12π CL

Cn1= CGS3+CDB1+CDB10 ≈ 3 CGS3

fnd = gm32π Cn1fT33

≈ Hi !

Page 27: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0727

Folded cascode CMOS OTA :

VDD

VSS

vOUT

M1 M2

M3 M4

+-

M9 M6

M10 M11

CL+

M7

M5

M8

6

35

4

2 1

7 GBW = gm1

2π CL

Cn5, Cn7 ,Cn6Cause poleand zeroat 2 x freq.:≈ 5 …10 o

Ref Mallya, JSSC Dec 89, 1737-1740

Page 28: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0728

Folded cascode BiCMOS OTA

VDD

VSS

vOUT

M1 M2

M3 M4

+-

M9 M6

M10 M11

CL

+

M83

5

2 1

GBW = gm1

2π CL

fnd =gm3

2π Cn1fT3NPN

3≈

Higher !

M6

M7

M5

M8

6

54

7

Page 29: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0729

Folded cascode OTA: input to Vss rail

VDD

VSS = 0 Volt

vOUTM1 M2

M3 M4+-

M9 M6

M10 M11

CL

+

M7

M5

M8

6

35

4

1

7

2

0.9 V

VT = 0.7 VVGS1-VT = 0.2 VVGS10-VT = 0.5 V

V+ = 1.5 VVGS3-VT = 0.2 V

0.7 V

+

Page 30: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0730

Folded cascode OTA with 2nd stage

VDD

VSS = 0 Volt

M1 M2

M3 M4+-

M9 M6

M10 M11

+

M7

M5

M8

6

35

4

1

7

2

+

vOUTCc

M12

M13

CL

8

No zero !

Ribner, JSSC Dec.84, 919-925

+

Page 31: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0731

Conventional folded cascode OTA

VDD

VSS = 0 Volt

vOUTM1 M2

M3 M4+-

M9 M6

M10 M11

CL

+

M7

M5

M8

6

35

4

1

7

2

+

+

Page 32: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0732

Alternative folded cascode OTA

VDD

VSS = 0 Volt

vOUTM1 M2

M3M4+-

M9

M10 M11

CL

3

5 4

1 2

+

gm1vINd

gm1vINd /2

M6

M7

M5

6

5 4

7

M8Current diff. amp.

Page 33: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0733

Comparison amplifiers

Telescopic 0.25 4 small

Folded casc. 0.5 4 avg.

Miller 2-stage (CL/Cc= 2.5) 1.1 4 max.

Volt. OTA (4 Ts) 0.25 4 avg.

Symmetrical (B= 3) 0.33 16 max.

ITOT dvin,eq2 Swing

GBW = 100 MHz CL = 2 pF VGS-VT = 0.2 V Fully differential

mA 8/3 kT dfgm1

Page 34: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0734

Table of contents

• Simple CMOS OTA• CMOS Miller OTA• Symmetrical CMOS OTA• Folded cascode OTA• Other opamps

Page 35: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0735

Sub-1 Volt OTA

Baschirotto, .. JSSC Dec.97,pp.1979-1986

1 V 80 µW (min: VT+2VDSsat)Fully differential75 dB 30 MHz (0.1 pF)< 100 ns

Level shifting M64 Switches 2n :Only 2nd stage switched off !

Page 36: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0736

LM 4250

GBW = 0.25 MHzSR = 0.2 V/µsI1 = 10 µA

ITOT = 90 µA38 nVRMS/√Hz

Page 37: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0737

Increased input transconductance - 1

vin

gmR =

RS

1 + gmRS

gm

iout

vin

gmR =

-RS

1 - gmRS

gm

iout

Page 38: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0738

Increased input transconductance - 2

vin

gm =1 +

gm1

iout

gm1gm2

M1

M2

vin

gm =1 -

gm1

iout

gm1gm2

M1

M2

-vin

Page 39: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0739

Ref.: Castello, JSSC June 1990, pp. 669-676

Increased input transconductance - 3

1 : 33 : 1

3 gmGBW =2πCL

CL

gm =1 -

gm1gm1gm3

gm ≈ 3 gm1

9 gm12πCL

≈M5,M6 for overdrive !

Page 40: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0740

Transconductor with C�DG compen.

VDS1 = RDID ≈ 0.2 V

IDS1 = β1VDS1(VGS1-VT)

gm1 = β1VDS1 is constant

Ref. Alini, JSSC, Dec.92, pp.1905-1915

Page 41: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0741

Ref. : Wu etal, JSSC Jan.1994, pp.63-66

14 MHz/ 11pF

5.6 MHz/ 100pF

4 V/µs

36 nV/√ Hz

5 V0.4 mA

gm1vin

gm3vin

Page 42: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0742

Problem: unequal gmtot

nMOST on :VINCM > 1.1 V

VINCMVSS = 0 VDD /2 VDD

gm

pMOST on : VINCM < VDD - 1.1 V

nMOSTpMOST

gmtot

1.1 V VDD-1.1 V

Increase gm:gmn+ gmp= ct

gmn gmp

Page 43: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0743

Wu : input rail-to-rail stage

VDD

2

VDD = 5V

0V

VDD

20

20

5

5

5

5

1010

10

10

20

20

20

0

0

20

5V

1.5V1.5V

pMOSTs off !

V+- high :

nMOSTs :IDS1 x 2gm1 x 2

Weak inv.

Page 44: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0744

Wu : output stage : gain

iin iin

RinRin

Rin Rin

iin

iin iin iin

Z

iin = gm1 v+-

vin

vin

vout

RL

vin

iin= Rin

voutvin

= 2gmA1RL

vout

iin= - 2RingmA1RL

Av = 2gm1RingmA1RL

Page 45: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0745

Wu : output quiescent current control

4 µA

VGS2 + VGS4 = VGS9 + VGS10

M4 = 2 M10 & M9 = M10

VGS2 - VT =IDS2

K’p W/L2

4 µA

IDS2

IDS9

W/L2

W/L9= (2 - ) ≈ 911

2

IDS2 ≈ 364 µA since IDS9 ≈ 4 µA

Page 46: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0746

Enhanced full-differential folded-cascode

Ref.Nakamura, JSSC April 1992, pp.563-568

CLCL

gm1GBW =2πCL

i = gm1vin

i/2

i/2+i/2

i

i/2

i/2

ii/2i/2

i/2i/2

Page 47: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0747

Bipolar opamp LM-124

GBW = 0.5 MHzSR = 0.4 V/µs

I1 = 3 µAITOT = 650 µA

68 nVRMS/√Hz

Page 48: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0748

BiFET opamp TL-070

GBW = 3 MHzSR = 13 V/µs

I1 = 100 µAITOT = 1400 µA18 nVRMS/√Hz

pS D G

pn

n

vGS0 vP

iDS

Page 49: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0749

Bipolar 2-stage opamp 741

GBW = 0.8 MHzSR = 0.7 V/µs

I1 = 10 µAITOT = 1100 µA14 nVRMS/√Hz

Page 50: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

Willy Sansen 10-05 0750

Two-stage opamp OP-97

trim

GBW = 0.8 MHzSR = 0.1 V/µsITOT = 600 µA25 µV offset30 pA input

+Vos -0 V

Page 51: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

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Bootstrap for high gain Av2

Ref.De Man JSSC June 77, pp.217-222

M1

M2

M3Rm

Rout

Rout -> x

Rm -> x β3

Av2 ≈ gm1 ro2 x β3

β3

1

Same GBW !

Page 52: Important opamp configurations - Springerextras.springer.com/2006/978-0-387-25746-4/Chapter_07.pdf · Important opamp configurations Willy Sansen KULeuven, ... Telescopic CMOS OTA

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Table of contents

• Simple CMOS OTA• CMOS Miller OTA• Symmetrical CMOS OTA• Folded cascode OTA• Other opamps


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