Class AB Output Stage With Short Circuit Protection

** Circuit Description **
* power supplies
Vcc+ 1 0 DC +15V
Vcc- 2 0 DC -15V
Ibias 0 5 DC 3mA
* input signal source
Vi 3 0 sin ( 0V 10V 1kHz )
* biasing diodes (transistors connected as diodes)
Q1 5 5 6 npn 
Q2 6 6 3 npn 
* output buffer (junction area of Qn and Qp is 3 times Qd1 and Qd2)
Qn 1 5 7 npn 3
Qp 2 3 8 pnp 3
Re1 7 4 10
Re2 8 4 10
* short circuit protection transistor
Qprotect 5 7 4 npn
* short circuit output terminal
Vshort 4 0 0
* simple transistor models
.model npn NPN  (Is=1e-13 Bf=50)
.model pnp PNP  (Is=1e-13 Bf=50)
** Analysis Requests **
.Tran 10us 3ms 0ms 10us
** Output Requests **
.Plot Tran V(1,7) i(Vcc+)
.probe
.end