* source follower buffer
vpos vdd 0 dc 15V
vneg vss 0 dc -15V
v1 vin 0 dc 7 ac 1 sin 0 1.41421V 1kHz
r1 vin 0 47k
j1 vdd vin vsj1 2n3819
r2 vdd vbq1 27k
q1 vsj1 vbq1 veq1 2n3904
r3 veq1 vss 150
q2 vbq1 veq1 vss 2n3904
c1 vsj1 vc1r4 3.9m
* r4 sets maximum distortion limit
r4 vc1r4 vr4r5 470
* adjust r5 from 0.1 to 4.7k (zero value resistances may cause simulation problems)
r5 vr4r5 0 4.7k
c2 vsj1 vout 180u
r6 vout 0 1meg
rl vout 0 47k
.MODEL 2N3819 NJF( VTO=-2.9985 BETA=1.3046M LAMBDA=2.2507M RD=1 RS=1 
+      CGD=1.5964P CGS=2.4199P PB=500M IS=33.582F 
+      BETATCE=-500M KF=0 AF=1 )
.model 2N3904 NPN (Is=6.734f Xti=3 Eg=1.11 Vaf=74.03 Bf=416.4 Ne=1.259
+               Ise=6.734f Ikf=66.78m Xtb=1.5 Br=.7371 Nc=2 Isc=0 Ikr=0 Rc=1
+               Cjc=3.638p Mjc=.3085 Vjc=.75 Fc=.5 Cje=4.493p Mje=.2593 Vje=.75
+               Tr=239.5n Tf=301.2p Itf=.4 Vtf=4 Xtf=2 Rb=10)
.end
.control
* transient analysis for 1k fourier
tran 1u 0.1 0 1u uic
fourier 1k vout
.endc