REV. E

OP297

–9–

3

D1

–IN

D2

Q1

R1

R2

R5

Q2

R6

10

11

G1

C3

R7

I1

D4

D3

R4

R3

C2

14

13

V3

E1

R8

C4

R9

V2

50

98

12

6

5

99

8

2

+IN

1

79

4

15

16

50

R16

R17

23

G4

G5

28 29

22

D6

D5 26

27

D7

D8

G6

R18

R19

D9

D10

G7

V4

V5

L1

25

99

98

9

R10

C5

G1

R11

R13

C6

C7

R12

E2

R14

E3

R15

C8

G3

Figure 15. Macro Model

To maintain accuracy, the negative supply should be well regu-

lated. For applications where very high accuracy is required, a

ation for the squaring circuit is that a sufficiently large input voltage

can force the output beyond the operating range of the output

can be varied to keep the output voltage within the usable range.

Unadjusted accuracy of the square-root circuit is better than 0.1%

over an input voltage range of 100 mV to 10 V. For a similar

input voltage range, the accuracy of the squaring circuit is better

than 0.5%.

OP297 SPICE MACRO MODEL

Figures 14 and 15 show the node end net list for a SPICE macro

model of the OP297. The model is a simplified version of the

rate, gain and phase response, and CMR change with frequency

are also simulated by the model.

The model uses typical parameters for the OP297. The poles

and zeros in the model were determined from the actual open-

and closed-loop gain and phase response of the OP297. In this

way, the model presents an accurate ac representation of the actual

device. The model assumes an ambient temperature of 25

°C.