98 lines
3.2 KiB
Plaintext
98 lines
3.2 KiB
Plaintext
Version 4
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SHEET 1 2168 1300
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WIRE 144 144 144 128
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WIRE -32 160 -80 160
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WIRE 112 160 -32 160
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WIRE -32 176 -32 160
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WIRE 384 176 176 176
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WIRE 672 176 464 176
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WIRE 944 176 672 176
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WIRE 112 192 80 192
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WIRE 672 192 672 176
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WIRE 144 224 144 208
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WIRE 944 224 944 176
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WIRE 1008 224 944 224
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WIRE 1008 240 1008 224
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WIRE -32 272 -32 256
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WIRE 192 272 96 272
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WIRE 288 272 256 272
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WIRE 672 288 672 272
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WIRE 1008 336 1008 320
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WIRE -80 352 -80 160
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WIRE 96 352 96 272
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WIRE 96 352 -80 352
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WIRE 128 352 96 352
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WIRE 288 352 288 272
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WIRE 288 352 208 352
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WIRE 944 352 944 224
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WIRE 944 352 288 352
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WIRE -224 416 -224 400
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WIRE -112 416 -112 400
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WIRE -224 512 -224 496
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WIRE -112 512 -112 496
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FLAG -112 512 0
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FLAG 80 192 0
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FLAG -32 272 0
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FLAG 1008 336 0
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FLAG 144 128 +V
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FLAG -112 400 +V
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FLAG -224 512 0
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FLAG -224 400 -V
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FLAG 144 224 -V
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FLAG 672 288 0
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FLAG 672 176 x
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SYMBOL voltage -112 400 R0
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WINDOW 123 0 0 Left 2
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WINDOW 39 0 0 Left 2
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SYMATTR InstName V1
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SYMATTR Value 15
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SYMBOL res 992 224 R0
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SYMATTR InstName R1
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SYMATTR Value 100
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SYMBOL res -48 160 R0
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SYMATTR InstName R2
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SYMATTR Value 1K
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SYMBOL res 224 336 R90
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WINDOW 0 0 56 VBottom 2
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WINDOW 3 32 56 VTop 2
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SYMATTR InstName R3
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SYMATTR Value 1K
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SYMBOL cap 256 256 R90
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WINDOW 0 0 32 VBottom 2
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WINDOW 3 32 32 VTop 2
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SYMATTR InstName C1
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SYMATTR Value 3p
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SYMBOL Opamps\\LT1001 144 112 R0
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WINDOW 0 27 42 Left 2
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WINDOW 3 25 87 Left 2
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SYMATTR InstName U1
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SYMBOL voltage -224 400 R0
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WINDOW 123 0 0 Left 2
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WINDOW 39 0 0 Left 2
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SYMATTR InstName V5
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SYMATTR Value -15
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SYMBOL current 672 272 M180
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WINDOW 0 24 77 Left 2
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WINDOW 3 24 0 Left 2
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WINDOW 123 37 33 Left 2
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WINDOW 39 0 0 Left 2
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SYMATTR InstName Ii
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SYMATTR Value ""
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SYMATTR Value2 AC {u(prb)}
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SYMBOL voltage 480 176 M270
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WINDOW 0 32 56 VTop 2
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WINDOW 3 -32 56 VBottom 2
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WINDOW 123 -32 56 VBottom 2
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WINDOW 39 -32 56 VBottom 2
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SYMATTR InstName Vi
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SYMATTR Value ""
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SYMATTR Value2 AC {u(-prb)}
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TEXT 360 416 Left 2 !.ac dec 30 .1 100Meg
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TEXT -8 -344 Left 2 ;Here the open loop gain is determined from the closed loop system[1].\nThe open loop gain can be plotted by plotting the quantity:\n \n-1/(1-1/(2*(I(Vi)@1*V(x)@2-V(x)@1*I(Vi)@2)+V(x)@1+I(Vi)@2))\n \nAlternatively, you add the following line to your plot.defs file:\n.func T.et.al() -1/(1-1/(2*(I(Vi)@1*V(x)@2-V(x)@1*I(Vi)@2)+V(x)@1+I(Vi)@2))\nAnd then plot simply T.et.al()\n \nThis is an improvement over the technique shown in LoopGain.asc \nbecause it (i) accounts for reverse feedback(it doesn't even\nmatter if you reverse the direction of the probe -- you still compute\nthe same open loop response) and (ii) the inserted probe elements\nresult in a smaller, sparser circuit matrix.
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TEXT 432 584 Top 1 ;This example schematic is supplied for informational/educational purposes only.
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TEXT -8 456 Left 2 ;[1] Michael Tian, V. Visvanathan, Jeffrey Hantgan, and Kenneth Kundert,\n "Striving for Small-Signal Stability", IEEE Circuits and Devices Magazine,\n vol. 17, no. 1, pp. 31-41, January 2001.
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TEXT 360 384 Left 2 !.step param prb list -1 1 ; set prb=0 to turn off probe
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TEXT 456 72 Left 2 ;Probe elements added to inject\nsignals to measure the open loop\nresponse from the closed loop system
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TEXT -328 560 Left 2 ;This example is based on posts contributed by Frank Wiedmann to the independent users' group at http://groups.yahoo.com/group/LTspice
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RECTANGLE Normal 912 320 336 48
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