Small-Signal BJT Models for µA741
The compact SoE for the open-loop voltage transmittance of the µA741
operational amplifier was generated using the classical hybrid-pi model
of a BJT adapted for three different device types (B.A. Wooley, S.-Y.J.
Wong, D.O. Pederson, "A Computer-Aided Evaluation of the 741 Amplifier,"
IEEE
J. Solid-State Circuits, vol. SC-6, Dec. 1971, pp. 357-366). The numerical
values of the small-signal model parameters were extracted from Spice simulation
using the Gummel-Poon model data from: G.R. Boyle, B.M. Cohn, D.O. Pederson,
J.E. Solomon, "Macromodeling of Integrated Circuit Operational Amplifiers,"
IEEE
J. Solid-State Circuits, vol. SC-9, Dec. 1974, pp. 353-363. These parameters
are summarised in the following table (the values are in kΩ, mS, pF).
Numbers in brackets () next to each BJT refer to the small-signal equivalent
circuit used to model the BJT:
(1) n-p-n device
(2) lateral p-n-p device
(3) substrate p-n-p device
| BJT |
gm |
rp |
rx |
ro |
Cp |
Cµ |
Cs |
rc |
|
Q1 (1)
|
0.489 |
455 |
0.670 |
15100 |
1.65 |
0.112 |
1.42 |
0.300 |
|
Q2 (1)
|
0.488 |
456 |
0.670 |
15200 |
1.65 |
0.112 |
1.42 |
0.300 |
|
Q3 (2)
|
0.514 |
165 |
0.500 |
4890 |
14.3 |
0.342 |
2.26 |
0.150 |
|
Q4 (2)
|
0.470 |
181 |
0.500 |
5340 |
13.1 |
0.345 |
2.26 |
0.150 |
|
Q5 (1)
|
0.484 |
427 |
0.670 |
14200 |
1.64 |
0.273 |
1.42 |
0.300 |
|
Q6 (1)
|
0.484 |
427 |
0.670 |
14200 |
1.64 |
0.247 |
1.42 |
0.300 |
|
Q7 (1)
|
0.470 |
510 |
0.670 |
16900 |
1.62 |
0.09 |
1.42 |
0.300 |
|
Q8 (2)
|
0.882 |
71.9 |
0.500 |
2230 |
24.4 |
1.05 |
2.26 |
0.150 |
|
Q9 (2)
|
1.13 |
71.9 |
0.500 |
2230 |
31.2 |
0.32 |
2.26 |
0.150 |
|
Q10 (1)
|
1.2 |
181 |
0.670 |
6090 |
2.49 |
0.112 |
1.42 |
0.300 |
|
Q11 (1)
|
21.5 |
5.11 |
0.670 |
245 |
25.9 |
0.447 |
1.42 |
0.300 |
|
Q12 (2)
|
15.3 |
0.813 |
0.500 |
81.2 |
419 |
1.13 |
2.26 |
0.150 |
|
Q13A (1)
|
3.65 |
3.78 |
0.100 |
22.9 |
100 |
0.3 |
2.26 |
0.080 |
|
Q13B (1)
|
9.11 |
1.62 |
0.160 |
9.17 |
250 |
1.0 |
2.26 |
0.120 |
|
Q14 (1)
|
6.07 |
67.4 |
0.185 |
1770 |
9.67 |
0.485 |
3.46 |
0.015 |
|
Q15 (1)
|
5E-11 |
2E+11 |
0.670 |
3E+10 |
0.65 |
0.36 |
1.42 |
0.300 |
|
Q16 (1)
|
0.571 |
418 |
0.670 |
13900 |
1.74 |
0.09 |
1.42 |
0.300 |
|
Q17 (1)
|
8.04 |
24.2 |
0.670 |
90 |
10.4 |
0.09 |
1.42 |
0.300 |
|
Q18 (1)
|
2.89 |
66 |
0.670 |
2290 |
4.46 |
0.273 |
1.42 |
0.300 |
|
Q19 (1)
|
0.628 |
326 |
0.670 |
1090 |
1.4 |
0.36 |
1.42 |
0.300 |
|
Q20 (3)
|
5.2 |
19.6 |
0.080 |
457 |
144 |
1.25 |
N/A |
0.156 |
|
Q21 (2)
|
8E-11 |
6.6E+10 |
0.500 |
6.7E+8 |
1.05 |
0.1 |
2.26 |
0.150 |
|
Q22 (1)
|
2E-15 |
2E+11 |
0.670 |
9.5E+8 |
0.65 |
0.3 |
1.42 |
0.300 |
|
Q23A (3)
|
2.41 |
131 |
1.100 |
998 |
65.7 |
1.09 |
N/A |
0.170 |
|
Q23B (3)
|
2E-15 |
2E+11 |
0.650 |
9.5E+8 |
1.9 |
2.4 |
N/A |
0.100 |
|
Q24 (1)
|
2E-15 |
2E+11 |
0.670 |
9.5E+8 |
0.65 |
0.36 |
1.42 |
0.300 |
Small-Signal Equivalent Circuits of BJTs used in µA741
n-p-n device (1)
Lateral p-n-p device (2)
Substrate p-n-p device (3)
