Voltage References (Ch. 23)g

김 영 석김 영 석

충북대학교 전자정보대학

2011.3.1. .

Email: kimys@cbu.ac.kr

전자정보대학 김영석 23-1

Contents23.1 MOSFET-Resistor Voltage References

23.2 Parasitic Diode-Based References

전자정보대학 김영석 23-2

PTAT/CTATPTAT(Proportional to absolute temperature)

CTAT(Complementary to absolute temperature)

전자정보대학 김영석 23-3

23.1 MOSFET-Resistor Voltage References23.1.1 The Resistor-MOSFET Divider

)(2

21 −=−

= VVR

VVDDI THNREFREF

Dβ

)4.23(11

=∂

∂=

Δ+=∴

TV

VTCV

VVV

REFREF

THNREF

Ex 23.1

∂TVREF

CppmTCVVV

REF

REF

°≈≈

/50085.1

R

CmVT

VNote THN

∂

°−≈∂

∂

1

/1:

CmVVCmVV

CppmTR

RTCR

TDiode °≈∂

°−≈∂

°≈∂∂

=

/0850/61

/20001

전자정보대학 김영석 23-4

CmVT

CmVT

≈∂

≈∂

/085.0,/6.1

23.1.2 The MOSFET-Only Voltage Divider

ββ

/

)(2

)(2

21

2221

⋅+−

−−=−

ββ

ββ

THNTHP

THPREFTHNREF

VVVDD

VVVDDVV

)1123(11//

21

21

∂

+

+=∴

ββββ

REF

THNTHPREF

VTCV

VVVDDV

4.1/:0

)11.23(

21 ==

=∂

=

ββREF

REF

REFREF

TCV

TVTCV

High Sensitivity to VDD

전자정보대학 김영석 23-5

23.1.3 Self-Biased Voltage ReferencesBMR(Beta-Multiplier Reference)

Low Sensitivity to VDD

? )1 StabilizedHow

↓↑↑↑↑↑↑

+<↓↓↓↓=>↑=>↑=> 21214,342

)2

)(, MMggdgg

VDDtoySensitivit

RRRvvivv Q

↓↑=>↑↑=>↑↑=>↑=> 4,34214,3 , dgggddd ivvviv

전자정보대학 김영석 23-6

Ex 23.2

Cascoding Not Useful for Short Channel Process

Use the Added Amplifier

전자정보대학 김영석 23-7

BMREx 23.3

CppmTCVmVV

REF

REF

°−≈=

/800500

전자정보대학 김영석 23-8

BMRAlternate Topology

)(,

)( ,

21212

2121

RRRvvivv

IICurrentSameRVV

MMggRoutg

DDGG

+<↓↓↓↓=>↓=>↑=>

==>=

Qggg

전자정보대학 김영석 23-9

23.2 Parasitic Diode-Based ReferencesParasitic PNP BJT의 VBE 이용

Diode in SPICE

4PNPDIODE02D2PNPDIODE 0 1 D1

eII nVV TD=

== 1N 18-1EIS D PNPDIODE .MODEL4PNPDIODE0 2 D2

/

CmVdTdV

eII

D

SDTD

°−=

=

/6.1

전자정보대학 김영석 23-10

Lower Voltage Reference Design

VREF=300mV

전자정보대학 김영석 23-11

23.2.1 Long-Channel BGR DesignCTAT: Diode-Referenced Self-Biasing

CTATeIR

VI nVVS

DREF

TD== )(/

CppmTCIIInVVV

REF

SREFTDREF

°−===

/4000)/ln(

PTAT: Thermal Voltage-Referenced Self-Biasing

PTATTKnkI

eIIRIVV

REF

nVVSDDDD

TD

⋅⋅

=

=+=

)(ln)( , /

221

TqR

KLnkV

PTATTqR

I

REF

REF

⋅⋅⋅

=ln

)(

CppmTCIqR

REF °≈ /1300

전자정보대학 김영석 23-12

Long-Channel BGRBandGap Reference

VVV

VKnLVRLIVV TDDREF

∂∂∂+=

⋅⋅⋅+=⋅⋅+=PTAT) CTAT(ZTC

ln33

TVCmVTVCmVTV

TVKnL

TV

TV

TD

TDREF

∂∂°=∂∂°−=∂∂

∂∂⋅⋅⋅+

∂∂

=∂

∂=

/)/085.0 / ,/6.1/(

ln0

3

3

CCLnK

TVTVKnL

T

D

°===

=∂∂∂∂

−=⋅⋅∴

/1214.9,1,8

8.18//ln 3

CppmTCVVV REFREF °≈≈ /17,2.1

전자정보대학 김영석 23-13

Alternative BGR

전자정보대학 김영석 23-14

23.2.2 Short-Channel BGR

VNKNnVV

RLVI

RKnVI

DTREF

DCTAT

TPTAT

ln

,ln

1

1

⋅+⋅⋅=

⋅=

⋅=

TV

LNKN

TVn

TV

VL

KNnVV

DTREF

DTREF

ln0

ln

1

1

∂∂⋅+⋅⋅

∂∂

=∂

∂=

+

LnKTVTVKnL

T

D

4.9,1,8

8.18//ln 1

===

=∂∂∂∂

−=⋅⋅∴

VVforLVKnV

VN REFDT

REF 5.0 91.3/ln 1

==+⋅

=

전자정보대학 김영석 23-15

Short-Channel BGR

전자정보대학 김영석 23-16