21

LT1251/LT1256

ACRO ODEL

*full scale amp

IBFS

12

0

–300NA

RIFS

12

0

100MEG

C12

12

0

1PF

R12

12

12A

1600

CBWFS

12A

0

10PF

EFS

12B

0

12A

0

1.0

VOSFS

12B

11

–5MV

C11

11

0

1PF

RFS

11

10

5K

C10

10

0

1PF

*

*generating K

*** the next two lines are for the LT1251

EK K 0 TABLE {I(VOSC)/I(VOSFS)}=

(–100,0)

(0.04,0)

(0.1,0.11)

+

(0.9,0.907) (0.95,1.0)

(100,1.0)

*** the next two lines are for the LT1256

*EK K 0 TABLE {I(VOSC)/I(VOSFS)}= (–100,0)

(0,0)

(0.2,0.21)

*+

(0.9,0.9)

(1.0,1.0)

(100,1.0)

RDUMMY

K

0

1MEG

RNOISE1

EN

0

200K

RNOISE2

EN

0

200K

*generates 40.7nV/rtHz

*

*null circuit

GNULL

7

6A

VALUE={I(VOSFS)}

RN1

6A

7

200

VNULL

6A

6B

0.0V

RN2

6B

6

400

C6

6

7

1PF

*

*output stage

E6

8A

0

+VALUE={1.8MEG*(I(VOS1)*V(K)+I(VOS2)*(1–V(K))–I(VNULL)+0.10UA+0.0007*V(EN))}

RG

8A

8B

1.8MEG

CG

8B

0

3.4PF

E8

8C

0

8B

0

1.0

V8

8C

8D

0.0V

R8

8D

8

11

*

*output swing and current limit

DP

8B

8P

D1

VDP

8P

9

–1.4V

DN

8N

8B

D1

VDN

8N

7

1.4V

.MODEL

D1

D

GCL

8B

0

TABLE {I(V8)}=(–1,–1)(–0.04,0)(0.04,0)(1,1)

*

*supply current

GQ

9

7

VALUE={1MA+24*I(VOSFS)+(V(7)–V(9))/20K}

GCC

9

0

TABLE {I(V8)}=(–1,0)(0,0)(1,1)

GEE

7

0

TABLE {I(V8)}=(–1,–1)(0,0)(1,0)

*

.ENDS LT1251