how to choose bjt for bandgap reference

[rengd02]

pnp tikf1

i want to design a bandgap reference that the branch current, Ic = 10ua
but I donot know how to choose the bjt, and the emitter area.

i have three pnp model:

10x10 5x5 2x2
*
.MODEL pnp10 PNP ( LEVEL = 1
+ BF = 1.79 NF = 0.95513 ISE = 3.7315E-18
+ NE = 1.069 IS = 3.7315E-18 RB = 140.9375822
+ IRB = 1.806256E-4 RBM = 0.1 RE = 3.717704
+ IKF = 2.568E-3 NKF = 0.5 VAF = 210.8833929
+ BR = 0.0101 NR = 0.94 ISC = 3.7315E-18
+ NC = 1.1616142 RC = 21.08 IKR = 1E-4
+ VAR = 17 XTI = 3 EG = 1.18
+ XTB = 0 TRB1 = 6.25612E-4 TIRB1 = 1.052303E-7
+ TRM1 = 9.44068E-6 TRE1 = -1.82691E-4 TIKF1 = -3.845646E-3
+ TIKR1 = -3.925072E-3 TRC1 = 0 TBR1 = 1.2E-4
+ TVAF1 = -6.950157E-5 TBF1 = 4E-3 TNC1 = 3.017315E-4
+ TNR1 = -1.50125E-4 TNF1 = -2.205635E-4 TNE1 = 1E-3
+ CJE = 1.181769E-13 VJE = 0.8661689 MJE = 0.3873499
+ FC = 0 CJC = 6.170502E-14 VJC = 0.6454517
+ MJC = 0.3487117 TLEVC = 1 CTE = 9.950871E-4
+ CTC = 2.347422E-3 TVJE = 1.685132E-3 TVJC = 2.929049E-3
+ TREF = 25 SUBS = 1 )
***************************************************************
* MODEL OF P+/NW/PSUB VERTICAL BIPOLAR *
* EMITTER AREA : 5 X 5 UM^2 *
***************************************************************
*
.MODEL pnp5 PNP ( LEVEL = 1
+ BF = 1.75 NF = 0.95513 ISE = 1E-18
+ NE = 1.069 IS = 1E-18 RB = 210.9375822
+ IRB = 1.806256E-4 RBM = 0.1 RE = 3.717704
+ IKF = 1.268E-3 NKF = 0.5 VAF = 210.8833929
+ BR = 4.3E-3 NR = 0.935 ISC = 1E-18
+ NC = 1 RC = 21.08 IKR = 1E-4
+ VAR = 17 XTI = 3 EG = 1.18
+ XTB = 0 TRB1 = 6.25612E-4 TIRB1 = 1.052303E-7
+ TRM1 = 9.44068E-6 TRE1 = -1.82691E-4 TIKF1 = -3.845646E-3
+ TIKR1 = -3.925072E-3 TRC1 = 0 TBR1 = 1.2E-4
+ TVAF1 = -6.950157E-5 TBF1 = 4E-3 TNC1 = 3.017315E-4
+ TNR1 = -1.50125E-4 TNF1 = -2.205635E-4 TNE1 = 1E-3
+ CJE = 1.181769E-13 VJE = 0.8661689 MJE = 0.3873499
+ FC = 0 CJC = 6.170502E-14 VJC = 0.6454517
+ MJC = 0.3487117 TLEVC = 1 CTE = 9.950871E-4
+ CTC = 2.347422E-3 TVJE = 1.685132E-3 TVJC = 2.929049E-3
+ TREF = 25 SUBS = 1 )
***************************************************************
* MODEL OF P+/NW/PSUB VERTICAL BIPOLAR *
* EMITTER AREA : 2 X 2 UM^2 *
***************************************************************
*
.MODEL pnp2 PNP ( LEVEL = 1
+ BF = 1.64 NF = 0.95513 ISE = 2.3E-19
+ NE = 1.069 IS = 2.3E-19 RB = 420.9375822
+ IRB = 1.806256E-4 RBM = 0.1 RE = 3.717704
+ IKF = 5E-4 NKF = 0.5 VAF = 210.8833929
+ BR = 1.36E-3 NR = 0.923 ISC = 2.3E-19
+ NC = 1 RC = 21.08 IKR = 1E-4
+ VAR = 15 XTI = 3 EG = 1.18
+ XTB = 0 TRB1 = 2.25612E-4 TIRB1 = 1.052303E-7
+ TRM1 = 9.44068E-6 TRE1 = -1.82691E-4 TIKF1 = 4E-4
+ TIKR1 = -3.925072E-3 TRC1 = 0 TBR1 = 1.2E-4
+ TVAF1 = -6.950157E-5 TBF1 = 4.4E-3 TNC1 = 3.017315E-4
+ TNR1 = -1.50125E-4 TNF1 = -1.205635E-4 TNE1 = 1E-3
+ CJE = 1.181769E-13 VJE = 0.8661689 MJE = 0.3873499
+ FC = 0 CJC = 6.170502E-14 VJC = 0.6454517
+ MJC = 0.3487117 TLEVC = 1 CTE = 9.950871E-4
+ CTC = 2.347422E-3 TVJE = 1.685132E-3 TVJC = 2.929049E-3
+ TREF = 25 SUBS = 1 )
*
thanks for guide

 

[bastos4321]

beta of substrate bjts

Chose the one with bigest area to improve matching.

Bastos

 

[swolf]

bandgap reference requirement

I agree with bastos

 

[fredflinstone]

with a collector current of 10uA the 10X10 substrate BJT may not have good beta. Though the biggest substrate BJT is better from matching point of view, you may have to increase the collector current to get good stable beta. So choose the one which matches ur power requirements as well as give good matching..