* SPICE netlist
RL V2s 0 {RL}
VIN Vpos 0 6.35
R1f V2s N007 1.5k
R2f N007 0 1.5k
Rs V2s V1s 0.1
Q2 N004 N004 N002 0 BC558B
Q3 N001 N004 N003 0 BC558B
Q4 N004 retro N009 0 BC548B
Q5 N001 Vref N009 0 BC548B
R1 Vpos N002 1k
R14 Vpos N003 1k
R15 Vpos N008 1k
Q6 N008 N008 0 0 BC548B
Q7 N009 N008 0 0 BC548B
M1 V1s N001 Vpos Vpos irf9540npbf
V2 Vref 0 2.5 AC 0
Q1 N001 N005 Vpos 0 BC558B
Q8 N005 0 0 0 BC548B
R17 Vpos N005 100k
C2 V2s N006 {CL}
C3 Vpos N001 2.2n
R2 N006 0 0.3
C1 V2s N007 470p
V1 P001 0 AC 1
C4 retro P001 10000
L1 N007 retro 10000
#MODELO TRANSISTORES
+Ikr=3.924 Rc=.9747 Cjc=5.25p Mjc=.3147 Vjc=.5697 Fc=.5 Cje=11.5p Mje=.6715 Vje=.5 Tr=10n Tf=410.2p Itf=1.491 Xtf=40.06 Vtf=10 Vceo=30 Icrating=100m mfg=Philips)
.ac dec 10 1 10g
.param RL= 50
.param CL= 2.2u
.step param RL list 5 100 130
.step param CL list 1u 2.2u 15u

* LTspice schematic (.asc)
Version 4
SHEET 1 2528 928
WIRE -976 -448 -1264 -448
WIRE -704 -448 -976 -448
WIRE -480 -448 -704 -448
WIRE -160 -448 -480 -448
WIRE -112 -448 -160 -448
WIRE -32 -448 -112 -448
WIRE 0 -448 -32 -448
WIRE 336 -448 96 -448
WIRE 656 -448 416 -448
WIRE 864 -448 656 -448
WIRE 1072 -448 864 -448
WIRE 1264 -448 1072 -448
WIRE -112 -416 -112 -448
WIRE 16 -352 16 -400
WIRE 16 -352 -112 -352
WIRE 336 -320 336 -448
WIRE 416 -320 416 -448
WIRE 336 -304 336 -320
WIRE 416 -304 416 -320
WIRE -704 -288 -704 -448
WIRE -480 -288 -480 -448
WIRE -160 -240 -160 -448
WIRE -704 -80 -704 -208
WIRE -480 -80 -480 -208
WIRE -32 -80 -32 -448
WIRE -1264 -32 -1264 -448
WIRE -592 -32 -640 -32
WIRE -544 -32 -592 -32
WIRE -160 -32 -160 -160
WIRE -160 -32 -224 -32
WIRE -96 -32 -160 -32
WIRE -224 -16 -224 -32
WIRE 16 16 16 -352
WIRE 16 16 -32 16
WIRE 1264 16 1264 -448
WIRE -416 32 -432 32
WIRE -320 32 -416 32
WIRE -288 32 -320 32
WIRE -272 32 -288 32
WIRE -704 48 -704 16
WIRE -592 48 -592 -32
WIRE -592 48 -704 48
WIRE 864 48 864 -448
WIRE -976 80 -976 -448
WIRE 656 96 656 -448
WIRE -480 144 -480 16
WIRE 16 144 16 16
WIRE 16 144 -480 144
WIRE -704 192 -704 48
WIRE -480 192 -480 144
WIRE 1072 192 1072 -448
WIRE 1264 224 1264 80
WIRE -768 240 -832 240
WIRE -320 240 -416 240
WIRE 656 240 656 176
WIRE 864 240 864 112
WIRE 864 240 656 240
WIRE -976 272 -976 160
WIRE -864 272 -976 272
WIRE 496 272 464 272
WIRE 544 272 496 272
WIRE 656 272 656 240
WIRE 656 272 624 272
WIRE -320 288 -320 240
WIRE -704 320 -704 288
WIRE -592 320 -704 320
WIRE -480 320 -480 288
WIRE -480 320 -592 320
WIRE -976 336 -976 272
WIRE -592 336 -592 320
WIRE 656 352 656 272
WIRE -912 384 -928 384
WIRE -864 384 -864 272
WIRE -864 384 -912 384
WIRE -656 384 -864 384
WIRE -1264 464 -1264 48
WIRE -976 464 -976 432
WIRE -976 464 -1264 464
WIRE -592 464 -592 432
WIRE -592 464 -976 464
WIRE -320 464 -320 368
WIRE -320 464 -592 464
WIRE -224 464 -224 80
WIRE -224 464 -320 464
WIRE 80 464 -224 464
WIRE 496 464 496 416
WIRE 496 464 80 464
WIRE 656 464 656 432
WIRE 656 464 496 464
WIRE 1072 464 1072 272
WIRE 1072 464 656 464
WIRE 1152 464 1072 464
WIRE 1264 464 1264 304
WIRE 1264 464 1152 464
FLAG 80 464 0
FLAG -1264 -448 Vpos
FLAG 336 -320 V1s
FLAG 416 -320 V2s
FLAG 1152 464 Vneg
FLAG -320 240 Vref
FLAG -832 240 retro
FLAG -416 32 Vopamp
FLAG -320 32 0
FLAG 464 272 retro
DATAFLAG 1040 -32 ""
DATAFLAG 96 -32 ""
SYMBOL res 1056 176 R0
SYMATTR InstName RL
SYMATTR Value {RL}
SYMBOL voltage -1264 -48 R0
SYMATTR InstName VIN
SYMATTR Value 6.35
SYMBOL res 640 80 R0
SYMATTR InstName R1f
SYMATTR Value 1.5k
SYMBOL res 640 336 R0
SYMATTR InstName R2f
SYMATTR Value 1.5k
SYMBOL res 432 -464 R90
SYMATTR InstName Rs
SYMATTR Value 0.1
SYMBOL pnp -640 16 R180
SYMATTR InstName Q2
SYMATTR Value BC558B
SYMBOL pnp -544 16 M180
SYMATTR InstName Q3
SYMATTR Value BC558B
SYMBOL npn -768 192 R0
SYMATTR InstName Q4
SYMATTR Value BC548B
SYMBOL npn -416 192 M0
SYMATTR InstName Q5
SYMATTR Value BC548B
SYMBOL res -720 -304 R0
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL res -496 -304 R0
SYMATTR InstName R14
SYMATTR Value 1k
SYMBOL res -992 64 R0
SYMATTR InstName R15
SYMATTR Value 1k
SYMBOL npn -912 336 M0
SYMATTR InstName Q6
SYMATTR Value BC548B
SYMBOL npn -656 336 R0
SYMATTR InstName Q7
SYMATTR Value BC548B
SYMBOL pmos 96 -400 M270
SYMATTR InstName M1
SYMATTR Value irf9540npbf
SYMBOL voltage -320 272 R0
SYMATTR InstName V2
SYMATTR Value 2.5
SYMATTR Value2 AC 0
SYMBOL pnp -96 16 M180
SYMATTR InstName Q1
SYMATTR Value BC558B
SYMBOL npn -288 -16 R0
SYMATTR InstName Q8
SYMATTR Value BC548B
SYMBOL res -176 -256 R0
SYMATTR InstName R17
SYMATTR Value 100k
SYMBOL Cap 1248 16 R0
SYMATTR InstName C2
SYMATTR Value {CL}
SYMBOL Cap -128 -416 R0
SYMATTR InstName C3
SYMATTR Value 2.2n
SYMBOL Res 1248 208 R0
SYMATTR InstName R2
SYMATTR Value 0.3
SYMBOL cap 848 48 R0
SYMATTR InstName C1
SYMATTR Value 470p
SYMBOL voltage 496 320 R0
SYMATTR InstName V1
SYMATTR Value ""
SYMATTR Value2 AC 1
SYMBOL cap 480 272 R0
SYMATTR InstName C4
SYMATTR Value 10000
SYMBOL ind 640 256 R90
SYMATTR InstName L1
SYMATTR Value 10000