* SPICE netlist
Vi N010 0 AC {1-z*z}
Iz N010 N008 AC {0.5*z*(z-1)}
Viy N008 N011 0
Vz N011 N012 AC {0.5*z*(z+1)}
Ey y 0 N010 N012 1
Rs N007 N010 100
V1 N009 N008 0
rm1 N007 N009 50
B1 N002 N007 I=I(V1)
R3 0 N002 200
V2 N001 0 0
rm2 N001 N002 200
B2 N003 N002 I=I(V2)
Cc N003 0 20p
R8 N003 0 10Meg
B3 0 N003 I=I(V3)
rm3 N003 N005 50
V3 N005 N004 0
B4 0 N004 I=I(V4)
rm4 N004 N006 10
V4 N006 o 0
R1 N012 0 100
R2 o N012 900
RL o 0 1k
.ac dec 100 100m 100G
.param z=0
.step param z list 1 0 -1

* LTspice schematic (.asc)
Version 4
SHEET 1 1392 1376
WIRE -232 -688 -392 -688
WIRE 248 -688 -232 -688
WIRE 536 -688 248 -688
WIRE 664 -688 536 -688
WIRE 664 -672 664 -688
WIRE -232 -624 -232 -688
WIRE -168 -624 -232 -624
WIRE -40 -624 -88 -624
WIRE -392 -576 -392 -688
WIRE -40 -560 -40 -624
WIRE 248 -560 248 -688
WIRE 536 -560 536 -688
WIRE -392 -432 -392 -496
WIRE -40 -432 -40 -480
WIRE -40 -432 -392 -432
WIRE 248 -432 248 -480
WIRE 248 -432 56 -432
WIRE 536 -432 536 -480
WIRE 536 -432 344 -432
WIRE -40 -400 -40 -432
WIRE 248 -400 248 -432
WIRE 536 -400 536 -432
WIRE -392 -336 -392 -432
WIRE 248 -272 248 -320
WIRE 536 -272 536 -320
WIRE -392 -208 -392 -256
WIRE -392 -208 -680 -208
WIRE -40 -208 -40 -320
WIRE -40 -208 -168 -208
WIRE 56 -208 56 -432
WIRE 56 -208 -40 -208
WIRE -680 -176 -680 -208
WIRE -392 -176 -392 -208
WIRE -168 -144 -168 -208
WIRE -40 -144 -40 -208
WIRE 248 -144 248 -192
WIRE 344 -144 344 -432
WIRE 344 -144 248 -144
WIRE -520 -48 -584 -48
WIRE -392 -48 -392 -96
WIRE -392 -48 -440 -48
WIRE -168 -16 -168 -64
WIRE -40 -16 -40 -80
WIRE -40 -16 -168 -16
WIRE -584 16 -584 -48
WIRE -328 16 -584 16
WIRE -40 16 -40 -16
WIRE -680 80 -680 -96
WIRE -520 80 -680 80
WIRE -328 80 -328 16
WIRE -328 80 -440 80
WIRE 536 112 536 -192
WIRE 632 112 536 112
WIRE 696 112 632 112
WIRE -328 144 -328 80
WIRE 696 208 696 112
WIRE -328 288 -328 224
WIRE 696 400 696 288
WIRE -568 416 -600 416
WIRE -536 416 -568 416
WIRE -424 416 -456 416
WIRE -424 432 -424 416
WIRE -680 464 -680 80
WIRE -520 464 -680 464
WIRE -328 464 -328 368
WIRE -328 464 -472 464
WIRE -680 528 -680 464
WIRE -328 528 -328 464
WIRE 152 528 -328 528
WIRE 344 528 152 528
WIRE 536 528 536 112
WIRE 536 528 424 528
WIRE 152 560 152 528
WIRE -680 688 -680 608
WIRE 152 688 152 640
FLAG -680 688 0
FLAG -424 432 0
FLAG -568 416 y
FLAG -40 16 0
FLAG 664 -672 0
FLAG 152 688 0
FLAG 696 400 0
FLAG 632 112 o
SYMBOL voltage -680 512 R0
SYMATTR Value2 AC {1-z*z}
SYMATTR InstName Vi
SYMATTR Value ""
SYMBOL current -520 80 R270
SYMATTR InstName Iz
SYMATTR Value ""
SYMATTR Value2 AC {0.5*z*(z-1)}
SYMBOL voltage -328 128 R0
SYMATTR InstName Viy
SYMATTR Value 0
SYMBOL voltage -328 272 M0
SYMATTR Value2 AC {0.5*z*(z+1)}
SYMATTR InstName Vz
SYMATTR Value ""
SYMBOL e -552 416 R270
SYMATTR InstName Ey
SYMATTR Value 1
SYMBOL res -696 -192 R0
SYMATTR InstName Rs
SYMATTR Value 100
SYMBOL voltage -424 -48 R90
SYMATTR InstName V1
SYMATTR Value 0
SYMBOL res -408 -192 R0
SYMATTR InstName rm1
SYMATTR Value 50
SYMBOL bi -392 -336 R0
SYMATTR InstName B1
SYMATTR Value I=I(V1)
SYMBOL res -408 -592 R0
SYMATTR InstName R3
SYMATTR Value 200
SYMBOL voltage -72 -624 R90
SYMATTR InstName V2
SYMATTR Value 0
SYMBOL res -56 -576 R0
SYMATTR InstName rm2
SYMATTR Value 200
SYMBOL bi -40 -320 R180
SYMATTR InstName B2
SYMATTR Value I=I(V2)
SYMBOL cap -56 -144 R0
SYMATTR InstName Cc
SYMATTR Value 20p
SYMBOL res -184 -160 R0
SYMATTR InstName R8
SYMATTR Value 10meg
SYMBOL bi 248 -560 R0
SYMATTR InstName B3
SYMATTR Value I=I(V3)
SYMBOL res 232 -416 R0
SYMATTR InstName rm3
SYMATTR Value 50
SYMBOL voltage 248 -288 R0
SYMATTR InstName V3
SYMATTR Value 0
SYMBOL bi 536 -560 R0
SYMATTR InstName B4
SYMATTR Value I=I(V4)
SYMBOL res 520 -416 R0
SYMATTR InstName rm4
SYMATTR Value 10
SYMBOL voltage 536 -288 R0
SYMATTR InstName V4
SYMATTR Value 0
SYMBOL res 136 544 R0
SYMATTR InstName R1
SYMATTR Value 100
SYMBOL res 440 512 R90
SYMATTR InstName R2
SYMATTR Value 900
SYMBOL res 680 192 R0
SYMATTR InstName RL
SYMATTR Value 1k