* SPICE netlist
Q1 N002 N005 N011 0 2N3904
Q2 N003 N005 N010 0 2N3904
Q3 N011 N009 N013 0 2N3904
Q4 N010 N008 N013 0 2N3904
D1 N005 N007 1N4148
D2 N007 0 1N4148
Q5 N001 N006 N008 0 2N3904
Q6 N001 0 N009 0 2N3904
R1 N008 N015 4.8k
R2 N009 N015 4.8k
Q7 N013 N012 N014 0 2N3904
R3 N014 N015 0.12k
V1 N006 0 AC 25m
R4 N001 N003 1.32k
R5 N001 N005 0.92k
R6 N001 N002 1.32k
R7 N004 0 5.25k
Q8 N001 N003 N004 0 2N3904
Q9 N001 N002 OUT 0 2N3904
R8 OUT 0 5.25k
R9 0 N012 2.93k
R10 N012 N015 0.67k
V2 N015 0 -6
V3 N001 0 6
.meas avgout AVG V(OUT)
.meas ppofout PP V(OUT)
.ac dec 100 1 100Meg

* LTspice schematic (.asc)
Version 4
SHEET 1 1840 1632
WIRE 712 -816 648 -816
WIRE -472 -688 -744 -688
WIRE -312 -688 -472 -688
WIRE -168 -688 -312 -688
WIRE 72 -688 -168 -688
WIRE 312 -688 72 -688
WIRE 712 -688 712 -816
WIRE 712 -688 312 -688
WIRE 728 -688 712 -688
WIRE -472 -576 -472 -688
WIRE -312 -576 -312 -688
WIRE -168 -576 -168 -688
WIRE 728 -496 728 -688
WIRE 312 -480 312 -688
WIRE 664 -448 552 -448
WIRE -472 -432 -472 -496
WIRE 248 -432 -472 -432
WIRE -168 -416 -168 -496
WIRE -88 -416 -168 -416
WIRE 728 -352 728 -400
WIRE 728 -352 712 -352
WIRE -88 -336 -88 -416
WIRE 552 -336 552 -448
WIRE 552 -336 -88 -336
WIRE 712 -304 712 -352
WIRE 888 -304 712 -304
WIRE 920 -304 888 -304
WIRE 312 -288 312 -384
WIRE -472 -256 -472 -432
WIRE -168 -256 -168 -416
WIRE 712 -256 712 -304
WIRE -312 -208 -312 -496
WIRE -312 -208 -408 -208
WIRE -232 -208 -312 -208
WIRE 312 -128 312 -208
WIRE 312 -128 296 -128
WIRE 376 -128 312 -128
WIRE 712 -128 712 -176
WIRE 712 -128 376 -128
WIRE -312 -112 -312 -208
WIRE 376 -80 376 -128
WIRE -744 -64 -744 -688
WIRE 72 -64 72 -688
WIRE -808 -16 -920 -16
WIRE 168 -16 136 -16
WIRE -312 0 -312 -48
WIRE 168 16 168 -16
WIRE -920 32 -920 -16
WIRE -744 64 -744 32
WIRE -616 64 -744 64
WIRE -744 80 -744 64
WIRE -312 80 -312 64
WIRE 72 80 72 32
WIRE 72 80 -56 80
WIRE 296 80 296 -128
WIRE -472 112 -472 -160
WIRE -168 112 -168 -160
WIRE 72 112 72 80
WIRE -920 160 -920 112
WIRE -616 160 -616 64
WIRE -536 160 -616 160
WIRE -56 160 -56 80
WIRE -56 160 -104 160
WIRE 296 240 296 160
WIRE 312 240 296 240
WIRE 312 272 312 240
WIRE 312 272 184 272
WIRE -472 336 -472 208
WIRE -312 336 -472 336
WIRE -168 336 -168 208
WIRE -168 336 -312 336
WIRE 312 352 312 272
WIRE -312 416 -312 336
WIRE 184 464 184 272
WIRE 184 464 -248 464
WIRE -312 544 -312 512
WIRE -744 672 -744 160
WIRE -312 672 -312 624
WIRE -312 672 -744 672
WIRE 72 672 72 192
WIRE 72 672 -312 672
WIRE 312 672 312 432
WIRE 312 672 72 672
WIRE 72 736 72 672
FLAG -312 80 0
FLAG -920 160 0
FLAG 168 16 0
FLAG 376 -80 0
FLAG 568 -816 0
FLAG 72 816 0
FLAG 888 -304 OUT
SYMBOL npn -232 -256 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL npn -408 -256 M0
SYMATTR InstName Q2
SYMATTR Value 2N3904
SYMBOL npn -104 112 M0
SYMATTR InstName Q3
SYMATTR Value 2N3904
SYMBOL npn -536 112 R0
SYMATTR InstName Q4
SYMATTR Value 2N3904
SYMBOL diode -328 -112 R0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode -328 0 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL npn -808 -64 R0
SYMATTR InstName Q5
SYMATTR Value 2N3904
SYMBOL npn 136 -64 M0
SYMATTR InstName Q6
SYMATTR Value 2N3904
SYMBOL res -760 64 R0
SYMATTR InstName R1
SYMATTR Value 4.8k
SYMBOL res 56 96 R0
SYMATTR InstName R2
SYMATTR Value 4.8k
SYMBOL npn -248 416 M0
SYMATTR InstName Q7
SYMATTR Value 2N3904
SYMBOL res -328 528 R0
SYMATTR InstName R3
SYMATTR Value 0.12k
SYMBOL voltage -920 16 R0
SYMATTR InstName V1
SYMATTR Value ""
SYMATTR Value2 AC 25m
SYMBOL res -488 -592 R0
SYMATTR InstName R4
SYMATTR Value 1.32k
SYMBOL res -328 -592 R0
SYMATTR InstName R5
SYMATTR Value 0.92k
SYMBOL res -184 -592 R0
SYMATTR InstName R6
SYMATTR Value 1.32k
SYMBOL res 296 -304 R0
SYMATTR InstName R7
SYMATTR Value 5.25k
SYMBOL npn 248 -480 R0
SYMATTR InstName Q8
SYMATTR Value 2N3904
SYMBOL npn 664 -496 R0
SYMATTR InstName Q9
SYMATTR Value 2N3904
SYMBOL res 696 -272 R0
SYMATTR InstName R8
SYMATTR Value 5.25k
SYMBOL res 280 64 R0
SYMATTR InstName R9
SYMATTR Value 2.93k
SYMBOL res 296 336 R0
SYMATTR InstName R10
SYMATTR Value 0.67k
SYMBOL voltage 72 720 R0
SYMATTR InstName V2
SYMATTR Value -6
SYMBOL voltage 664 -816 R90
SYMATTR InstName V3
SYMATTR Value 6