bandgap reference circuit - alab.ee.nctu.edu.t · bandagap output voltage (v) temperature (o c) tt...
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Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
1National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference circuit 307暑期訓練課程
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
2National Chiao Tung University國立交通大學
ICS Lab.
General Considerations
To generate a voltage or current reference that is independent of the supply voltage and process and has a well-defined behavior with temperature.
The required temperature dependence assumes one of three forms :• Proportional to absolute temperature (PTAT)• Constant-Gm behavior• Temperature independent
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
3National Chiao Tung University國立交通大學
ICS Lab.
General Considerations
The sensitivity of a parameter y to a second one x is defined as
The variation of a parameter y that results from changes in temperature is usually characterized by its fractional temperature coefficient, which is defined as the fractional change per degree centigrade change in temperature
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
4National Chiao Tung University國立交通大學
ICS Lab.
Simple Current Sources The output current of the circuit is quite sensitive to VDD
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
5National Chiao Tung University國立交通大學
ICS Lab.
Supply-Independent Biasing Supply-Independent Current Generator (ΔVGS reference)
Output current is determined by K and RS
The current is independent of the supply voltage, but still a function of process and temperature.
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
6National Chiao Tung University國立交通大學
ICS Lab.
Temperature independent References If a reference is temperature independent, then it is usually process-
independent as well. If two quantities having opposite temperature coefficients (TCs) are added
with proper weighting, the result displays a zero TC. To obtain a reference voltage with zero TC
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
7National Chiao Tung University國立交通大學
ICS Lab.
Temperature independent References The forward voltage of a PN-junction diode exhibits a negative TC.
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
8National Chiao Tung University國立交通大學
ICS Lab.
Temperature independent References PTAT Generator
If two identical transistors (IS1 = IS2) are biased at collector currents of nI0and I0 , and their base currents are negligible
Thus, VBE difference exhibits a positive temperature coefficient
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
9National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference example Kujik Bandgap reference
Vos is amplified by 1+R2/R3 Vos itself varies with temperature, raising the temperature coefficient of the
output voltage.
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
10National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference example
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
11National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference Output Issues
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
12National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference schematic
185
35
213
213
25
25
123
123
810
25
25
810
8 p
0.2210
0.55
100.5
0.845
0.845
119k119k
13k
65
65
2npn 2npn
10 p10M
Transistor level implementation of bandgap referenceThe gain-enhanced OPAMP
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
13National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference schematic
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
14National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference schematic
-40 -20 0 20 40 60 80 1001.215
1.220
1.225
1.230
1.235
1.240
1.245Ba
ndag
ap O
utpu
t Vol
tage
(V)
Temperature (oC)
TT FF SS
Nanoelectronics and Gigascale Systems Lab.奈米電子與晶片系統實驗室
15National Chiao Tung University國立交通大學
ICS Lab.
Bandgap reference Specs.
Parameter SpecificationTechnology CIC 0.18umSupply voltage 1.8vReference voltage 1.225v@27℃Static current Consumption 26.3uATC @ VDD=1.8v 25ppm/℃PSR @ 10kHz 90.3dB