power management circuits - hanyangsoc.hanyang.ac.kr/kor/classes/undergraduate... · 2018-10-10 ·...
TRANSCRIPT
Outline and References• Introduction
• Linear Voltage Regulators
• Charge Pumps
• Inductor-type Switching Converters
References
1. Power Management Techniques for Integrated Circuit Design, K.-H. Chen.
2. CMOS VLSI Design, fourth edition, Weste & Harris.
3. Fundamentals of Power Electronics, second edition, Erickson & Maksimovic.
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Introduction
3
PMIC (Power Management IC)
4
LCD Bias
PMIC
Smart Phone
PMIC
LED
PMIC
Battery
PMIC
Provide stable output voltage for electronic equipment with high power efficiency
Great increase in market
General Structure of Power Management ICs
5
PMIC – Display Applications
6
LED backlight driver - Thin and light
- Simple circuit
- Mercury free
- Low voltage driving
- Low power consumption
- Low temperature operation
- Fast response: wide dimming range
- Easy channel balancing[ LED backlight driver ]
Electric Vehicles
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Vehicle is not mechanical product anymore- It is becoming electric/electronic product
[ LED backlight driver ]
PMIC – Mobile Applications
8
Mobile system includes various functions even if its battery-based power system.
Multi-output voltages are necessary for various function blocks.
[ Smart PMIC block diagram ][ Mobile system block diagram ]
PMIC– Mobile Applications, cont’d
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“A highly integrated power management IC foradvanced mobile applications”, IEEE JSSC 2007.by Qualcomm
Power Management Units
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• Typical Linear Voltage Regulators
• Low Drop-Out Regulators
Linear Voltage Regulators
• Switched-Capacitor (or Charge Pump) Converters
• Inductor-Type Switching Converters
Switching Power Converters
Linear Voltage Regulators
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Linear Regulators
(a) Regulator with source follower output stage
12
_
+VREF
IBIAS ILOADC
M0
VIN
A0
VG
VOUT
VSS
(c) Common-source output stage
Linear Regulators
Output capacitor with equivalent series resistance (ESR)
13
Linear Regulators
Pass transistor types. (a) NPN Darlington, (b) NPN, (c) PNP, (d) NMOS, (e) PMOS, (f) NMOS with charge pump
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Linear Regulators
각 pass transistor type 별장단점
15
Linear Regulators
(a) 기본적인 LDO regulator 의회로도
(b) pole-splitting with Miller capacitance CGD. (no output capacitor)
16
Linear Regulators
(a) Large output capacitor for sudden load current variation
(b) Root locus of poles due to the output capacitor
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Linear Regulators
주파수특성을좋게하기위한 buffer stage 추가
(Buffer 추가로 pass transistor 의 gate 단에서의저항성분감소목적)
18
Linear Regulators
Buffer stage 의구현예 (기본적인 source follower 회로)
19
Linear Regulators
향상된 buffer 회로예 (feedback 을통한 buffer 의 output resistance 감소)
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Charge Pumps
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Charge Pump 응용예 – Flash Memory 1
NAND Flash Memory (Toshiba 1989)
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64Gb NAND Flash Memory (Toshiba 2009)
Charge Pump 응용예 – Flash Memory 2
NAND Flash string.
(ssl: string select line, gsl: ground select line)
• word 신호들은 active low 신호임.
• 총 16개 word 신호들중선택된한개만 low, 나머지는모두 high.
• 각 bit line 들은 pull-up 되어있음.
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Floating gate NMOS transistor,
& Erase and Program operations
Charge Pump 회로예
Diode 를사용한회로예
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CMOS 회로구현예
Charge Pump 설계예
(잘못된설계예임. 수업시간토론목적.)
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Inductor-Type SwitchingConverters
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Inductor and Capacitor
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vL
iL1
CiCv 1
2
21 vCW
2
21
LiLW
dt
dt
(J)
(J)
C
iC
v
iL L
v
Current:
Energy:
Current:
Energy:
Converter
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+
v(t)
-
R
Vg(t)
+
vs(t)
-
DTs Ts t
Vs(t)
Vg
On Off
offon
on
TTTCycleDuty
ggss
T
ss
Tss DVVDTT
dttvT
vs
)(1)(10
Duty Cycle
SPDT switch and a load
Buck Converter
+
v(t)
-
C R
L
Vg
12
iL(t)
Switch1 Switch2
+
V(t)
-
C R
L
Vg
iL(t)+
V(t)
-
C R
L
Vg iL(t)
Buck Converter
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Buck Converter analysis
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Switch1
Inductor voltage and Capacitor current
Small ripple approximation :
)(tvvv gL
VVv gL
Switch2
Inductor voltage and Capacitor current
Small ripple approximation :
)(tvvL
VvL
Rtvii Lc /)(
RVIic /
Rtvii Lc /)(
RVIic /
Inductor volt-second balance: applied to inductor over one switching period
Equation to zero and collect terms
The voltage conversion ratio is therefore
ssg
Ts
L TDVDTVVdttv ')()()(0
0)'( DDVDVg gDVV
DVVDM
g
)(
Buck Converter analysis
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Voltage ripple
t
V
Actual waveform v(t)=V+Vripple(t)
DC component V
Actual output voltage
Waveform
In a well-designed converter, the output voltage ripple is small. Hence the waveform can be easily approximated by ignoring ripple
-> Small ripple approximation
VtvVv
tvVtv
ripple
ripple
)(,
)()(
Small Ripple Approximation
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Boost Converter
33
Boost Converter
Switch1 Switch2
+
V
-
C R
L
Vg
)(tiL+
V(t)
-
C R
L
Vg
)(tiL
Boost Converter analysis
34
Net volt-seconds applied to inductor over one switching period
Equation to zero and collect terms
The voltage conversion ratio is therefore
t
VL(t)
Vg
DTs D`Ts
Vg-V
sgsg
Ts
L TDVVDTVdttv ')()()(0
0')'( VDDDVg
DDVVDM
g
11
'1)(
'DV
V g
Boost Converter analysis
35
Switch1
Inductor voltage and Capacitor current
Small ripple approximation :
Switch2
Inductor voltage and Capacitor current
Small ripple approximation :
Rvivv cgL /
RViVv cgL /
Rviivvv LcgL /
RvIivVv cgL /
Boost Converter analysis
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Capacitor charge balance
Collect terms and equate to zero
Eliminate V to express in terms of Vg
ssTs
c TDRVIDT
RVdtti ')()()(
0
0')'( IDDDRV
RDVI'
RD
VI g
'2
t
iC(t)
-V/R
DTs D`Ts
I - V/R
Basic Buck Converter• Basic DC-DC converter without
protection circuits
37
VoutL
CR1
R2
Rload
Vg
compensator
bufferand
deadtimecontroller
S-Rlatchsawtooth
wavegenerator
comparator
clock
error ampVFB
Vref
reset
S
R
Qclock
generator
Vc
Sawtooth Waveform
• Sawtooth waveform and clock generator
38
Vb
VCC
Ib
M1
clock
Comparator
Vsawtooth
C
Buffer and Non-Overlapping Circuit
• Large power transistor requires buffer block• Non-overlapping to reduce shoot-through current in
power transistor
39
Pdr_b
Ndr
VCC
VSS
VCC
VSS
PI Compensator
• OTA and external R-C components
40
1C
1R2C
OTAVc
OTA Error Amplifier• Conventional Mirror OTA
– Load cap=10pF– Tail current=200uA, quiescent output current=400uA
• Cascoded output may be used for higher gain– Drawback: limited output swing
41
VpVn
Vo
M1 M2
M3 M4
It
M0
M6
M8M7
M5
Vss414 1
Vb
High-Performance Error Amp.• Gain Boosting Technique
• Load cap=10pF• Tail current=200uA, quiescent output current=40uA
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VpVnVo
M1 M2
M3 M4
It
M0
M6
M8M7
M5
Vcc
Vss
M9 M10
M12M11
M13 M14
41814 1 8 1
Vb
Current Sense Schemes• Current sense resistor in series with power transistor
• Most accurate technique• Additional resistance causes higher power loss
• Use turn-on resistance of power transistor for current sense
• Turn-on resistance varies too much for process, temperature, etc.
• Current sense circuits• accurate• Circuit design is complicated• Extra quiescent current loss
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Current Sense Circuit• Current sense circuit for Buck converter
44
MP2
R
CO
L1
_ +
MS2
MR
M2 M1
MP1
MS1
MN1
VC
IO
VO
I1I1
VB
VQ
IP1IP2
Isen
Vadd
VIN
VA
VIN
VQ
Thank you.
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