Version 4 SHEET 1 1192 972 WIRE 384 -16 192 -16 WIRE 576 -16 464 -16 WIRE -80 96 -144 96 WIRE -16 96 -80 96 WIRE 192 96 192 -16 WIRE 192 96 64 96 WIRE 256 96 192 96 WIRE 384 96 256 96 WIRE -144 160 -144 96 WIRE 384 160 384 96 WIRE 432 160 384 160 WIRE 576 176 576 -16 WIRE 576 176 496 176 WIRE 752 176 576 176 WIRE 432 192 384 192 WIRE -144 272 -144 240 WIRE 384 272 384 192 WIRE 384 272 -144 272 WIRE -144 304 -144 272 FLAG -144 304 0 FLAG 752 176 OUT FLAG -80 96 IN FLAG 256 96 INV- SYMBOL res 80 80 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R1 SYMATTR Value 1k SYMBOL res 480 -32 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value {Rfdbk} SYMBOL voltage -144 144 R0 WINDOW 3 28 85 Left 2 WINDOW 123 28 113 Left 2 SYMATTR Value SINE(0 100mV 1000) SYMATTR Value2 AC 1 0 SYMATTR InstName V1 SYMBOL Opamps/opamp 464 112 R0 WINDOW 3 -3 103 Left 2 SYMATTR Value small_signal_opamp C_op=C Gm_op=Gm R_op=R SYMATTR SpiceLine "" SYMATTR SpiceLine2 "" SYMATTR InstName U1 TEXT 576 296 Left 2 !.subckt small_signal_opamp 3 2 1\n* connections: | | |\n* -ve input | |\n* +ve input |\n* output\nGinput 0 4 2 3 {Gm_op}\nR1 4 0 {R_op}\nC1 4 0 {C_op}\nEoutput 1 0 4 0 1\n.ends small_signal_opamp TEXT -96 416 Left 2 !.PARAM C=30p Gm=0.190m R=1323Meg TEXT -160 472 Left 2 !.step param Rfdbk LIST 1k 10k 100k 1000k 1000Meg TEXT -40 360 Left 2 !.AC DEC 5 0.1Hz 100MegHz