Version 4
SHEET 1 880 700
WIRE -48 144 -80 144
WIRE 16 144 -48 144
WIRE 192 144 96 144
WIRE 256 144 192 144
WIRE 16 176 16 144
WIRE 96 176 96 144
WIRE -80 256 -80 144
WIRE 192 256 192 144
WIRE 16 288 16 256
WIRE 96 288 96 256
WIRE 96 288 16 288
WIRE 16 320 16 288
WIRE 96 320 96 288
WIRE -80 448 -80 336
WIRE -48 448 -80 448
WIRE 16 448 16 400
WIRE 16 448 -48 448
WIRE 96 448 96 400
WIRE 192 448 192 336
WIRE 192 448 96 448
WIRE 256 448 192 448
WIRE -80 464 -80 448
WIRE 208 528 80 528
WIRE 80 560 80 528
WIRE 208 560 208 528
WIRE 80 672 80 640
WIRE 208 672 208 640
WIRE 208 672 80 672
WIRE 80 688 80 672
FLAG -48 144 3
FLAG -48 448 4
FLAG 256 144 1
FLAG 256 448 2
FLAG -80 464 0
FLAG 80 688 0
FLAG 208 528 B
SYMBOL res 0 160 R0
SYMATTR InstName R10a
SYMATTR Value {R10/2}
SYMBOL current -80 336 R180
WINDOW 0 24 80 Left 2
WINDOW 3 24 0 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName I1
SYMATTR Value {I1}
SYMBOL current 80 640 R180
WINDOW 0 24 80 Left 2
WINDOW 3 24 0 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName I2
SYMATTR Value PULSE(-1 1 0 1 1 1 5 1)
SYMBOL res 192 544 R0
SYMATTR InstName R2
SYMATTR Value 1
SYMBOL res 0 304 R0
SYMATTR InstName R10b
SYMATTR Value {R10/2}
SYMBOL res 80 160 R0
SYMATTR InstName R20a
SYMATTR Value {R20/2}
SYMBOL res 80 304 R0
SYMATTR InstName R20b
SYMATTR Value {R20/2}
SYMBOL bi 192 336 M180
WINDOW 0 24 80 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName B1
SYMATTR Value I=V(B)*(KB0*(I(R10a)+I(R10b))/(2*R20))
TEXT -96 8 Left 2 !.param R10=1k
TEXT -96 24 Left 2 !.param R20=1k
TEXT -96 40 Left 2 !.param KB0=200 ;V/AT
TEXT -96 -16 Left 2 !.tran 1 startup
TEXT -96 56 Left 2 !,param I1=5m
TEXT -8 56 Left 2 !.step param I1 list 4m 5m 6m