For amdx: - Kleijer amplifier reworked.

F

Fred Abse

Guest
Examination of a full model of the whole circuit revealed that the
parallel input resistance would actually go negative somewhere around
1MHz, exactly where dependent on source resistance.

I got interested, and finished up doing a rework, addressing:

Negative input resistance.

Gain not unity, as claimed. Actually 4dB.

Output operating point nowhere near Vcc/2, hence reduced output swing.

Output impedance nearer 60 ohms than the claimed 50.

The enclosed Spice simulation of the reworked circuit shows:

Gain 0.17dB at 500KHz.

Input resistance 37Meg in parallel with 254fF. (at 500kHz)

More or less symmetrical clipping.

Output VSWR 1.06, at 500kHz.

It's still a POS, but it's now *my* POS :)

Try it just don't put half a microhenry of input leads on it,
like in the original author's photograph.

Plot file included at end.

Version 4
SHEET 1 2052 680
WIRE 432 -240 -256 -240
WIRE -256 -176 -256 -240
WIRE -112 -176 -256 -176
WIRE 0 -176 -32 -176
WIRE 208 -176 0 -176
WIRE 432 -176 432 -240
WIRE 640 -176 432 -176
WIRE 1104 -176 640 -176
WIRE 1280 -176 1104 -176
WIRE -256 -160 -256 -176
WIRE 0 -144 0 -176
WIRE 992 -128 896 -128
WIRE 1104 -128 1104 -176
WIRE 1104 -128 1072 -128
WIRE 208 -80 208 -176
WIRE -256 -64 -256 -80
WIRE 432 -64 432 -176
WIRE 0 -32 0 -80
WIRE 896 -32 896 -48
WIRE 1088 -32 896 -32
WIRE 1088 0 1088 -32
WIRE 640 32 640 -176
WIRE 1280 32 1280 -176
WIRE 432 48 432 16
WIRE 464 48 432 48
WIRE 208 64 208 0
WIRE 304 64 208 64
WIRE 592 64 576 64
WIRE 768 64 752 64
WIRE 896 64 896 48
WIRE 896 64 832 64
WIRE 896 80 896 64
WIRE 1216 80 896 80
WIRE 208 96 208 64
WIRE 432 96 432 48
WIRE 464 96 464 48
WIRE 512 96 512 64
WIRE 512 96 464 96
WIRE 896 96 896 80
WIRE 512 128 512 96
WIRE 592 128 592 64
WIRE 592 128 576 128
WIRE 640 128 640 112
WIRE 640 128 592 128
WIRE 1280 144 1280 128
WIRE -80 160 -144 160
WIRE 64 160 -16 160
WIRE 160 160 64 160
WIRE 1488 160 1456 160
WIRE 1584 160 1552 160
WIRE 640 176 640 128
WIRE 896 176 896 160
WIRE 64 208 64 160
WIRE 304 224 304 64
WIRE 336 224 304 224
WIRE 432 224 432 176
WIRE 432 224 400 224
WIRE 576 224 432 224
WIRE 1088 224 1088 64
WIRE 1280 224 1088 224
WIRE 1344 224 1280 224
WIRE 1456 224 1456 160
WIRE 1456 224 1424 224
WIRE 1584 224 1584 160
WIRE 1648 224 1584 224
WIRE 1712 224 1648 224
WIRE -144 240 -144 160
WIRE 208 240 208 192
WIRE 1280 240 1280 224
WIRE 896 256 896 240
WIRE 1456 256 1456 224
WIRE 1488 256 1456 256
WIRE 1584 256 1584 224
WIRE 1584 256 1552 256
WIRE 640 304 640 272
WIRE 752 304 752 64
WIRE 752 304 640 304
WIRE 432 320 432 224
WIRE 1648 320 1648 224
WIRE 64 336 64 288
WIRE 640 336 640 304
WIRE 896 336 896 320
WIRE 1152 336 896 336
WIRE 1280 336 1280 320
WIRE 752 352 752 304
WIRE 784 352 752 352
WIRE 896 352 896 336
WIRE 896 352 848 352
WIRE 1088 352 1088 224
WIRE 896 384 896 352
WIRE 1152 384 1152 336
WIRE 1216 384 1152 384
WIRE 896 480 896 464
WIRE 1088 480 1088 416
WIRE 1088 480 896 480
WIRE -144 576 -144 320
WIRE 64 576 64 416
WIRE 64 576 -144 576
WIRE 208 576 208 320
WIRE 208 576 64 576
WIRE 432 576 432 400
WIRE 432 576 208 576
WIRE 640 576 640 416
WIRE 640 576 432 576
WIRE 896 576 896 560
WIRE 896 576 640 576
WIRE 1280 576 1280 432
WIRE 1280 576 896 576
WIRE 1648 576 1648 400
WIRE 1648 576 1280 576
WIRE 64 640 64 576
FLAG -256 -64 0
FLAG 64 640 0
FLAG -144 160 in
IOPIN -144 160 In
FLAG 1712 224 out
IOPIN 1712 224 Out
FLAG 0 -32 0
SYMBOL njf 160 96 R0
SYMATTR InstName J1
SYMATTR Value BF256C
SYMBOL res 192 224 R0
SYMATTR InstName R1
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 48 192 R0
SYMATTR InstName R2
SYMATTR Value 10meg
SYMATTR SpiceLine tol=1
SYMBOL cap -16 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 0.3p
SYMBOL voltage -256 -176 R0
WINDOW 123 0 0 Left 2
WINDOW 39 24 28 Left 2
SYMATTR SpiceLine Rser=1
SYMATTR InstName Vcc
SYMATTR Value 12
SYMBOL res 48 320 R0
SYMATTR InstName R3
SYMATTR Value 10meg
SYMATTR SpiceLine tol=1
SYMBOL voltage -144 224 R0
WINDOW 123 24 106 Left 2
WINDOW 39 24 116 Left 2
WINDOW 3 24 30 Left 2
SYMATTR Value2 AC 1
SYMATTR SpiceLine Rser=0
SYMATTR Value SINE(0 1 500k)
SYMATTR InstName V2
SYMBOL cap 400 208 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL res 416 416 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R4
SYMATTR Value 9.1k
SYMBOL res 416 192 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 2k
SYMBOL res 416 32 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R6
SYMATTR Value 24
SYMBOL res 624 128 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R7
SYMATTR Value 47
SYMBOL cap 576 144 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C3
SYMATTR Value 10u
SYMBOL cap 576 80 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C4
SYMATTR Value 100n
SYMBOL res 624 432 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R8
SYMATTR Value 470
SYMBOL diode 880 96 R0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 880 176 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL diode 880 256 R0
SYMATTR InstName D3
SYMATTR Value 1N4148
SYMBOL cap 832 48 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 100n
SYMBOL cap 848 336 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value 100n
SYMBOL res 880 -48 R0
SYMATTR InstName R9
SYMATTR Value 6.8k
SYMBOL res 880 -144 R0
SYMATTR InstName R10
SYMATTR Value 3.9k
SYMBOL res 880 368 R0
SYMATTR InstName R11
SYMATTR Value 6.8k
SYMBOL res 880 464 R0
SYMATTR InstName R12
SYMATTR Value 3.3k
SYMBOL cap 1072 0 R0
SYMATTR InstName C7
SYMATTR Value 100n
SYMBOL cap 1072 352 R0
SYMATTR InstName C8
SYMATTR Value 100n
SYMBOL npn 1216 32 R0
SYMATTR InstName Q2
SYMATTR Value BC547B
SYMBOL pnp 1216 336 R0
SYMATTR InstName Q3
SYMATTR Value BC557B
SYMBOL res 1264 128 R0
SYMATTR InstName R13
SYMATTR Value 10
SYMBOL res 1264 224 R0
SYMATTR InstName R14
SYMATTR Value 10
SYMBOL res 1440 208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 18
SYMBOL res 1632 304 R0
SYMATTR InstName R16
SYMATTR Value 10k
SYMBOL cap 1552 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C9
SYMATTR Value 1u
SYMBOL cap 1552 240 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C10
SYMATTR Value 100n
SYMBOL res 1088 -144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R17
SYMATTR Value 33k
SYMBOL res 192 -96 R0
SYMATTR InstName R18
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL pnp 576 272 M180
SYMATTR InstName Q1
SYMATTR Value BFT92
SYMATTR Prefix X
SYMBOL res -16 -160 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R19
SYMATTR Value 100
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap -16 -144 R0
SYMATTR InstName C11
SYMATTR Value 1u
SYMATTR SpiceLine V=10 Irms=10.541 Rser=0.004 Lser=0 mfg="KEMET" pn="C0603C105K8PAC" type="X5R"
TEXT 872 -408 Left 2 !.ac lin 10000 10k 1g
TEXT 872 -376 Left 2 !.net V(Out) v2 Rout=50
TEXT 256 -312 Left 2 !.model BF256C NJF(Beta=1.4m Betatce=-.5 Rd=1 Rs=1 Lambda=4.6m Vto=-3.1\n+ Vtotc=-2.5m Is=33.57f Isr=322.4f N=1 Nr=2 Xti=3 Alpha=311.7u\n+ Vk=243.6 Cgd=2.132p M=.3622 Pb=1 Fc=.5 Cgs=2.104p Kf=23.06E-18\n+ Af=1)
TEXT 872 -448 Left 2 !.opt plotwinsize=0\n.opt numdgt=16
TEXT 1384 -664 Left 2 !* Filename: BFT92_SPICE.PRM\n* BFT92 SPICE MODEL\n* PHILIPS SEMICONDUCTORS\n* Date : September 1995\n*\n* PACKAGE : SOT23 DIE MODEL : BFT92\n* 1: COLLECTOR; 2: BASE; 3: EMITTER;\n.SUBCKT BFT92 1 2 3\nQ1 6 5 7 7 BFT92\n* SOT23 parasitic model\n Lb 4 5 .4n \n Le 7 8 .83n\n L1 2 4 .35n\n L2 1 6 .17n\n L3 3 8 .35n\n Ccb 4 6 71f\n Cbe 4 8 2f\n Cce 6 8 71f\n* PHILIPS SEMICONDUCTORS Version: 2.0\n* Filename: BFT92.PRM Date: July 1992\n*\n.MODEL BFT92 PNP\n+ IS = 4.37563E-016\n+ BF = 3.35815E+001\n+ NF = 1.00972E+000\n+ VAF = 2.33946E+001\n+ IKF = 9.95381E-002\n+ ISE = 8.70539E-014\n+ NE = 1.94395E+000\n+ BR = 4.94721E+000\n+ NR = 1.00254E+000\n+ VAR = 3.90385E+000\n+ IKR = 5.28157E-003\n+ ISC = 3.58864E-014\n+ NC = 1.39333E+000\n+ RB = 5.00000E+000\n+ IRB = 1.00000E-006\n+
RBM = 5.00000E+000\n+ RE = 1.00000E+000\n+ RC = 1.00000E+001\n+ EG = 1.11000E+000\n+ XTI = 3.00000E+000\n+ CJE = 7.46659E-013\n+ VJE = 6.00000E-001\n+ MJE = 3.56829E-001\n+ TF = 1.74921E-011\n+ XTF = 1.35455E+000\n+ VTF = 1.55654E-001\n+ ITF = 1.00000E-003\n+ PTF = 4.50000E+001\n+ CJC = 9.37103E-013\n+ VJC = 3.96455E-001\n+ MJC = 1.99949E-001\n.ENDS
TEXT 264 -104 Left 3 ;Gets rid of negative\ninput resistance\nthat was occuring\nabove ~ 1MHz
TEXT 480 -104 Left 3 ;Sets overall\ngain ~1
TEXT 1072 -88 Left 3 ;Sets output stage\noperating point\n~Vcc/2
TEXT 504 240 Left 3 ;Changed to\nPNP to\npreserve\noutput polarity
TEXT 1352 304 Left 3 ;Value changed\nfor more\naccurate\n50 ohm O/P
TEXT -112 -48 Left 3 ;No need for a\nridiculous\ndecoupling\n"Ghrismas Tree"\nof capaciors.\nA (properly selected)\nsingle should be\nfine.
RECTANGLE Normal 384 96 128 -128 2
RECTANGLE Normal 560 32 400 -128 2
RECTANGLE Normal 1184 -48 944 -224 2
RECTANGLE Normal 704 304 496 176 2
RECTANGLE Normal 1456 384 1328 128 2
RECTANGLE Normal 112 96 -144 -208 2

[AC Analysis]
{
Npanes: 4
Active Pane: 3
{
traces: 1 {3,0,"(1+S22(v2))/(1-S22(v2))"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',1,0.7,0.1,1.7)
Y[1]: (' ',0,-32,4,16)
Log: 1 0 0
GridStyle: 1
PltMag: 1
Text: "" 1 (318761.751521045,1.75612244897959) ;Output VSWR 50 ohm
},
{
traces: 1 {5,0,"1/RE(Yin(v2))"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('_',1,1000,0,1e+009)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (331739.531535957,2053525026.45715) ;Parallel input resistance
},
{
traces: 1 {2,0,"IM((Yin(v2)))/2/pi/freq"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('f',0,2.28e-013,3e-015,2.64e-013)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (337484.183978161,2.66207094420198e-013) ;Parallel input capacitance
},
{
traces: 1 {524292,0,"V(out)"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',0,0.0794328234724281,2,1)
Y[1]: (' ',0,-240,30,90)
Log: 1 2 0
GridStyle: 1
PltMag: 1
PltPhi: 1 0
Text: "" 1 (341818.444827778,1.14101582205948) ;Gain
}
}


--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On 2/28/2014 3:40 PM, Fred Abse wrote:
Examination of a full model of the whole circuit revealed that the
parallel input resistance would actually go negative somewhere around
1MHz, exactly where dependent on source resistance.

I got interested, and finished up doing a rework, addressing:

Negative input resistance.

Gain not unity, as claimed. Actually 4dB.
Click to expand...

I think that's very dependent on the gimmick capacitor.
My cap is slightly bigger than what he says his is,

Output operating point nowhere near Vcc/2, hence reduced output swing.
Click to expand...

5vpp output swing at clipping.
At 3vpp, the sinewave starts to show some distortion, rounding of
the upper side.
All unterminated. (1MHz)

Output impedance nearer 60 ohms than the claimed 50.
Click to expand...

When I put a 50 ohm termination on the output the amplitude drops by
half. (1MHz)

The enclosed Spice simulation of the reworked circuit shows:

Gain 0.17dB at 500KHz.
Click to expand...

(1Mhz) Hard to see any difference between the input and output amplitude

looks like the output is inverted and has a phase delay of 40ns at 1MHz.


Input resistance 37Meg in parallel with 254fF. (at 500kHz)
Click to expand...

Remember the circuits purpose was to be able to connect to a high Q LC
circuit and measure Q while not causing a change in the Q.
That's a pretty light load!

More or less symmetrical clipping.
Click to expand...

Yes.

Output VSWR 1.06, at 500kHz.

It's still a POS, but it's now *my* POS :)
Click to expand...

Oh, btw, I didn't use his 5GHz transistor, it oscillated.
I used a 2n3904.
Mikek
Try it just don't put half a microhenry of input leads on it,
like in the original author's photograph.

Plot file included at end.

Version 4
SHEET 1 2052 680
WIRE 432 -240 -256 -240
WIRE -256 -176 -256 -240
WIRE -112 -176 -256 -176
WIRE 0 -176 -32 -176
WIRE 208 -176 0 -176
WIRE 432 -176 432 -240
WIRE 640 -176 432 -176
WIRE 1104 -176 640 -176
WIRE 1280 -176 1104 -176
WIRE -256 -160 -256 -176
WIRE 0 -144 0 -176
WIRE 992 -128 896 -128
WIRE 1104 -128 1104 -176
WIRE 1104 -128 1072 -128
WIRE 208 -80 208 -176
WIRE -256 -64 -256 -80
WIRE 432 -64 432 -176
WIRE 0 -32 0 -80
WIRE 896 -32 896 -48
WIRE 1088 -32 896 -32
WIRE 1088 0 1088 -32
WIRE 640 32 640 -176
WIRE 1280 32 1280 -176
WIRE 432 48 432 16
WIRE 464 48 432 48
WIRE 208 64 208 0
WIRE 304 64 208 64
WIRE 592 64 576 64
WIRE 768 64 752 64
WIRE 896 64 896 48
WIRE 896 64 832 64
WIRE 896 80 896 64
WIRE 1216 80 896 80
WIRE 208 96 208 64
WIRE 432 96 432 48
WIRE 464 96 464 48
WIRE 512 96 512 64
WIRE 512 96 464 96
WIRE 896 96 896 80
WIRE 512 128 512 96
WIRE 592 128 592 64
WIRE 592 128 576 128
WIRE 640 128 640 112
WIRE 640 128 592 128
WIRE 1280 144 1280 128
WIRE -80 160 -144 160
WIRE 64 160 -16 160
WIRE 160 160 64 160
WIRE 1488 160 1456 160
WIRE 1584 160 1552 160
WIRE 640 176 640 128
WIRE 896 176 896 160
WIRE 64 208 64 160
WIRE 304 224 304 64
WIRE 336 224 304 224
WIRE 432 224 432 176
WIRE 432 224 400 224
WIRE 576 224 432 224
WIRE 1088 224 1088 64
WIRE 1280 224 1088 224
WIRE 1344 224 1280 224
WIRE 1456 224 1456 160
WIRE 1456 224 1424 224
WIRE 1584 224 1584 160
WIRE 1648 224 1584 224
WIRE 1712 224 1648 224
WIRE -144 240 -144 160
WIRE 208 240 208 192
WIRE 1280 240 1280 224
WIRE 896 256 896 240
WIRE 1456 256 1456 224
WIRE 1488 256 1456 256
WIRE 1584 256 1584 224
WIRE 1584 256 1552 256
WIRE 640 304 640 272
WIRE 752 304 752 64
WIRE 752 304 640 304
WIRE 432 320 432 224
WIRE 1648 320 1648 224
WIRE 64 336 64 288
WIRE 640 336 640 304
WIRE 896 336 896 320
WIRE 1152 336 896 336
WIRE 1280 336 1280 320
WIRE 752 352 752 304
WIRE 784 352 752 352
WIRE 896 352 896 336
WIRE 896 352 848 352
WIRE 1088 352 1088 224
WIRE 896 384 896 352
WIRE 1152 384 1152 336
WIRE 1216 384 1152 384
WIRE 896 480 896 464
WIRE 1088 480 1088 416
WIRE 1088 480 896 480
WIRE -144 576 -144 320
WIRE 64 576 64 416
WIRE 64 576 -144 576
WIRE 208 576 208 320
WIRE 208 576 64 576
WIRE 432 576 432 400
WIRE 432 576 208 576
WIRE 640 576 640 416
WIRE 640 576 432 576
WIRE 896 576 896 560
WIRE 896 576 640 576
WIRE 1280 576 1280 432
WIRE 1280 576 896 576
WIRE 1648 576 1648 400
WIRE 1648 576 1280 576
WIRE 64 640 64 576
FLAG -256 -64 0
FLAG 64 640 0
FLAG -144 160 in
IOPIN -144 160 In
FLAG 1712 224 out
IOPIN 1712 224 Out
FLAG 0 -32 0
SYMBOL njf 160 96 R0
SYMATTR InstName J1
SYMATTR Value BF256C
SYMBOL res 192 224 R0
SYMATTR InstName R1
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 48 192 R0
SYMATTR InstName R2
SYMATTR Value 10meg
SYMATTR SpiceLine tol=1
SYMBOL cap -16 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 0.3p
SYMBOL voltage -256 -176 R0
WINDOW 123 0 0 Left 2
WINDOW 39 24 28 Left 2
SYMATTR SpiceLine Rser=1
SYMATTR InstName Vcc
SYMATTR Value 12
SYMBOL res 48 320 R0
SYMATTR InstName R3
SYMATTR Value 10meg
SYMATTR SpiceLine tol=1
SYMBOL voltage -144 224 R0
WINDOW 123 24 106 Left 2
WINDOW 39 24 116 Left 2
WINDOW 3 24 30 Left 2
SYMATTR Value2 AC 1
SYMATTR SpiceLine Rser=0
SYMATTR Value SINE(0 1 500k)
SYMATTR InstName V2
SYMBOL cap 400 208 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL res 416 416 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R4
SYMATTR Value 9.1k
SYMBOL res 416 192 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 2k
SYMBOL res 416 32 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R6
SYMATTR Value 24
SYMBOL res 624 128 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R7
SYMATTR Value 47
SYMBOL cap 576 144 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C3
SYMATTR Value 10u
SYMBOL cap 576 80 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C4
SYMATTR Value 100n
SYMBOL res 624 432 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R8
SYMATTR Value 470
SYMBOL diode 880 96 R0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 880 176 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL diode 880 256 R0
SYMATTR InstName D3
SYMATTR Value 1N4148
SYMBOL cap 832 48 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 100n
SYMBOL cap 848 336 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value 100n
SYMBOL res 880 -48 R0
SYMATTR InstName R9
SYMATTR Value 6.8k
SYMBOL res 880 -144 R0
SYMATTR InstName R10
SYMATTR Value 3.9k
SYMBOL res 880 368 R0
SYMATTR InstName R11
SYMATTR Value 6.8k
SYMBOL res 880 464 R0
SYMATTR InstName R12
SYMATTR Value 3.3k
SYMBOL cap 1072 0 R0
SYMATTR InstName C7
SYMATTR Value 100n
SYMBOL cap 1072 352 R0
SYMATTR InstName C8
SYMATTR Value 100n
SYMBOL npn 1216 32 R0
SYMATTR InstName Q2
SYMATTR Value BC547B
SYMBOL pnp 1216 336 R0
SYMATTR InstName Q3
SYMATTR Value BC557B
SYMBOL res 1264 128 R0
SYMATTR InstName R13
SYMATTR Value 10
SYMBOL res 1264 224 R0
SYMATTR InstName R14
SYMATTR Value 10
SYMBOL res 1440 208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 18
SYMBOL res 1632 304 R0
SYMATTR InstName R16
SYMATTR Value 10k
SYMBOL cap 1552 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C9
SYMATTR Value 1u
SYMBOL cap 1552 240 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C10
SYMATTR Value 100n
SYMBOL res 1088 -144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R17
SYMATTR Value 33k
SYMBOL res 192 -96 R0
SYMATTR InstName R18
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL pnp 576 272 M180
SYMATTR InstName Q1
SYMATTR Value BFT92
SYMATTR Prefix X
SYMBOL res -16 -160 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R19
SYMATTR Value 100
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap -16 -144 R0
SYMATTR InstName C11
SYMATTR Value 1u
SYMATTR SpiceLine V=10 Irms=10.541 Rser=0.004 Lser=0 mfg="KEMET" pn="C0603C105K8PAC" type="X5R"
TEXT 872 -408 Left 2 !.ac lin 10000 10k 1g
TEXT 872 -376 Left 2 !.net V(Out) v2 Rout=50
TEXT 256 -312 Left 2 !.model BF256C NJF(Beta=1.4m Betatce=-.5 Rd=1 Rs=1 Lambda=4.6m Vto=-3.1\n+ Vtotc=-2.5m Is=33.57f Isr=322.4f N=1 Nr=2 Xti=3 Alpha=311.7u\n+ Vk=243.6 Cgd=2.132p M=.3622 Pb=1 Fc=.5 Cgs=2.104p Kf=23.06E-18\n+ Af=1)
TEXT 872 -448 Left 2 !.opt plotwinsize=0\n.opt numdgt=16
TEXT 1384 -664 Left 2 !* Filename: BFT92_SPICE.PRM\n* BFT92 SPICE MODEL\n* PHILIPS SEMICONDUCTORS\n* Date : September 1995\n*\n* PACKAGE : SOT23 DIE MODEL : BFT92\n* 1: COLLECTOR; 2: BASE; 3: EMITTER;\n.SUBCKT BFT92 1 2 3\nQ1 6 5 7 7 BFT92\n* SOT23 parasitic model\n Lb 4 5 .4n \n Le 7 8 .83n\n L1 2 4 .35n\n L2 1 6 .17n\n L3 3 8 .35n\n Ccb 4 6 71f\n Cbe 4 8 2f\n Cce 6 8 71f\n* PHILIPS SEMICONDUCTORS Version: 2.0\n* Filename: BFT92.PRM Date: July 1992\n*\n.MODEL BFT92 PNP\n+ IS = 4.37563E-016\n+ BF = 3.35815E+001\n+ NF = 1.00972E+000\n+ VAF = 2.33946E+001\n+ IKF = 9.95381E-002\n+ ISE = 8.70539E-014\n+ NE = 1.94395E+000\n+ BR = 4.94721E+000\n+ NR = 1.00254E+000\n+
VAR = 3.90385E+000\n+ IKR = 5.28157E-003\n+ ISC = 3.58864E-014\n+ NC = 1.39333E+000\n+ RB = 5.00000E+000\n+ IRB = 1.00000E-006\n+ RBM = 5.00000E+000\n+ RE = 1.00000E+000\n+ RC = 1.00000E+001\n+ EG = 1.11000E+000\n+ XTI = 3.00000E+000\n+ CJE = 7.46659E-013\n+ VJE = 6.00000E-001\n+ MJE = 3.56829E-001\n+ TF = 1.74921E-011\n+ XTF = 1.35455E+000\n+ VTF = 1.55654E-001\n+ ITF = 1.00000E-003\n+ PTF = 4.50000E+001\n+ CJC = 9.37103E-013\n+ VJC = 3.96455E-001\n+ MJC = 1.99949E-001\n.ENDS
TEXT 264 -104 Left 3 ;Gets rid of negative\ninput resistance\nthat was occuring\nabove ~ 1MHz
TEXT 480 -104 Left 3 ;Sets overall\ngain ~1
TEXT 1072 -88 Left 3 ;Sets output stage\noperating point\n~Vcc/2
TEXT 504 240 Left 3 ;Changed to\nPNP to\npreserve\noutput polarity
TEXT 1352 304 Left 3 ;Value changed\nfor more\naccurate\n50 ohm O/P
TEXT -112 -48 Left 3 ;No need for a\nridiculous\ndecoupling\n"Ghrismas Tree"\nof capaciors.\nA (properly selected)\nsingle should be\nfine.
RECTANGLE Normal 384 96 128 -128 2
RECTANGLE Normal 560 32 400 -128 2
RECTANGLE Normal 1184 -48 944 -224 2
RECTANGLE Normal 704 304 496 176 2
RECTANGLE Normal 1456 384 1328 128 2
RECTANGLE Normal 112 96 -144 -208 2

[AC Analysis]
{
Npanes: 4
Active Pane: 3
{
traces: 1 {3,0,"(1+S22(v2))/(1-S22(v2))"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',1,0.7,0.1,1.7)
Y[1]: (' ',0,-32,4,16)
Log: 1 0 0
GridStyle: 1
PltMag: 1
Text: "" 1 (318761.751521045,1.75612244897959) ;Output VSWR 50 ohm
},
{
traces: 1 {5,0,"1/RE(Yin(v2))"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('_',1,1000,0,1e+009)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (331739.531535957,2053525026.45715) ;Parallel input resistance
},
{
traces: 1 {2,0,"IM((Yin(v2)))/2/pi/freq"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('f',0,2.28e-013,3e-015,2.64e-013)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (337484.183978161,2.66207094420198e-013) ;Parallel input capacitance
},
{
traces: 1 {524292,0,"V(out)"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',0,0.0794328234724281,2,1)
Y[1]: (' ',0,-240,30,90)
Log: 1 2 0
GridStyle: 1
PltMag: 1
PltPhi: 1 0
Text: "" 1 (341818.444827778,1.14101582205948) ;Gain
}
}
Click to expand...
 
On 2/28/2014 9:11 PM, amdx wrote:
On 2/28/2014 3:40 PM, Fred Abse wrote:
Examination of a full model of the whole circuit revealed that the
parallel input resistance would actually go negative somewhere around
1MHz, exactly where dependent on source resistance.

I got interested, and finished up doing a rework, addressing:
Click to expand...
Do you have any part value changes to improve the circuit.
Not interested in building a whole new board, but it would be nice
to reduce the distortion and increase the output before clipping.
Just for fun.
Remember the amps use, to provide a high resistance, low capacitance
load to a high Q LC circuit, with an output to drive a scope or meter.

Thanks, Mikek
 
HALT!
All the data I gave below will be in error, I found my 12 volt regulator
is defective. Probably for the reason given in the update.
Mikek




On 2/28/2014 9:11 PM, amdx wrote:
On 2/28/2014 3:40 PM, Fred Abse wrote:
Examination of a full model of the whole circuit revealed that the
parallel input resistance would actually go negative somewhere around
1MHz, exactly where dependent on source resistance.

I got interested, and finished up doing a rework, addressing:

Negative input resistance.

Gain not unity, as claimed. Actually 4dB.

I think that's very dependent on the gimmick capacitor.
My cap is slightly bigger than what he says his is,


Output operating point nowhere near Vcc/2, hence reduced output swing.

5vpp output swing at clipping.
At 3vpp, the sinewave starts to show some distortion, rounding of
the upper side.
All unterminated. (1MHz)


Output impedance nearer 60 ohms than the claimed 50.

When I put a 50 ohm termination on the output the amplitude drops by
half. (1MHz)


The enclosed Spice simulation of the reworked circuit shows:

Gain 0.17dB at 500KHz.

(1Mhz) Hard to see any difference between the input and output amplitude

looks like the output is inverted and has a phase delay of 40ns at 1MHz.



Input resistance 37Meg in parallel with 254fF. (at 500kHz)

Remember the circuits purpose was to be able to connect to a high Q LC
circuit and measure Q while not causing a change in the Q.
That's a pretty light load!


More or less symmetrical clipping.

Yes.

Output VSWR 1.06, at 500kHz.

It's still a POS, but it's now *my* POS :)

Oh, btw, I didn't use his 5GHz transistor, it oscillated.
I used a 2n3904.
Mikek

Try it just don't put half a microhenry of input leads on it,
like in the original author's photograph.

Plot file included at end.

Version 4
SHEET 1 2052 680
WIRE 432 -240 -256 -240
WIRE -256 -176 -256 -240
WIRE -112 -176 -256 -176
WIRE 0 -176 -32 -176
WIRE 208 -176 0 -176
WIRE 432 -176 432 -240
WIRE 640 -176 432 -176
WIRE 1104 -176 640 -176
WIRE 1280 -176 1104 -176
WIRE -256 -160 -256 -176
WIRE 0 -144 0 -176
WIRE 992 -128 896 -128
WIRE 1104 -128 1104 -176
WIRE 1104 -128 1072 -128
WIRE 208 -80 208 -176
WIRE -256 -64 -256 -80
WIRE 432 -64 432 -176
WIRE 0 -32 0 -80
WIRE 896 -32 896 -48
WIRE 1088 -32 896 -32
WIRE 1088 0 1088 -32
WIRE 640 32 640 -176
WIRE 1280 32 1280 -176
WIRE 432 48 432 16
WIRE 464 48 432 48
WIRE 208 64 208 0
WIRE 304 64 208 64
WIRE 592 64 576 64
WIRE 768 64 752 64
WIRE 896 64 896 48
WIRE 896 64 832 64
WIRE 896 80 896 64
WIRE 1216 80 896 80
WIRE 208 96 208 64
WIRE 432 96 432 48
WIRE 464 96 464 48
WIRE 512 96 512 64
WIRE 512 96 464 96
WIRE 896 96 896 80
WIRE 512 128 512 96
WIRE 592 128 592 64
WIRE 592 128 576 128
WIRE 640 128 640 112
WIRE 640 128 592 128
WIRE 1280 144 1280 128
WIRE -80 160 -144 160
WIRE 64 160 -16 160
WIRE 160 160 64 160
WIRE 1488 160 1456 160
WIRE 1584 160 1552 160
WIRE 640 176 640 128
WIRE 896 176 896 160
WIRE 64 208 64 160
WIRE 304 224 304 64
WIRE 336 224 304 224
WIRE 432 224 432 176
WIRE 432 224 400 224
WIRE 576 224 432 224
WIRE 1088 224 1088 64
WIRE 1280 224 1088 224
WIRE 1344 224 1280 224
WIRE 1456 224 1456 160
WIRE 1456 224 1424 224
WIRE 1584 224 1584 160
WIRE 1648 224 1584 224
WIRE 1712 224 1648 224
WIRE -144 240 -144 160
WIRE 208 240 208 192
WIRE 1280 240 1280 224
WIRE 896 256 896 240
WIRE 1456 256 1456 224
WIRE 1488 256 1456 256
WIRE 1584 256 1584 224
WIRE 1584 256 1552 256
WIRE 640 304 640 272
WIRE 752 304 752 64
WIRE 752 304 640 304
WIRE 432 320 432 224
WIRE 1648 320 1648 224
WIRE 64 336 64 288
WIRE 640 336 640 304
WIRE 896 336 896 320
WIRE 1152 336 896 336
WIRE 1280 336 1280 320
WIRE 752 352 752 304
WIRE 784 352 752 352
WIRE 896 352 896 336
WIRE 896 352 848 352
WIRE 1088 352 1088 224
WIRE 896 384 896 352
WIRE 1152 384 1152 336
WIRE 1216 384 1152 384
WIRE 896 480 896 464
WIRE 1088 480 1088 416
WIRE 1088 480 896 480
WIRE -144 576 -144 320
WIRE 64 576 64 416
WIRE 64 576 -144 576
WIRE 208 576 208 320
WIRE 208 576 64 576
WIRE 432 576 432 400
WIRE 432 576 208 576
WIRE 640 576 640 416
WIRE 640 576 432 576
WIRE 896 576 896 560
WIRE 896 576 640 576
WIRE 1280 576 1280 432
WIRE 1280 576 896 576
WIRE 1648 576 1648 400
WIRE 1648 576 1280 576
WIRE 64 640 64 576
FLAG -256 -64 0
FLAG 64 640 0
FLAG -144 160 in
IOPIN -144 160 In
FLAG 1712 224 out
IOPIN 1712 224 Out
FLAG 0 -32 0
SYMBOL njf 160 96 R0
SYMATTR InstName J1
SYMATTR Value BF256C
SYMBOL res 192 224 R0
SYMATTR InstName R1
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 48 192 R0
SYMATTR InstName R2
SYMATTR Value 10meg
SYMATTR SpiceLine tol=1
SYMBOL cap -16 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C1
SYMATTR Value 0.3p
SYMBOL voltage -256 -176 R0
WINDOW 123 0 0 Left 2
WINDOW 39 24 28 Left 2
SYMATTR SpiceLine Rser=1
SYMATTR InstName Vcc
SYMATTR Value 12
SYMBOL res 48 320 R0
SYMATTR InstName R3
SYMATTR Value 10meg
SYMATTR SpiceLine tol=1
SYMBOL voltage -144 224 R0
WINDOW 123 24 106 Left 2
WINDOW 39 24 116 Left 2
WINDOW 3 24 30 Left 2
SYMATTR Value2 AC 1
SYMATTR SpiceLine Rser=0
SYMATTR Value SINE(0 1 500k)
SYMATTR InstName V2
SYMBOL cap 400 208 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL res 416 416 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R4
SYMATTR Value 9.1k
SYMBOL res 416 192 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 2k
SYMBOL res 416 32 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R6
SYMATTR Value 24
SYMBOL res 624 128 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R7
SYMATTR Value 47
SYMBOL cap 576 144 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C3
SYMATTR Value 10u
SYMBOL cap 576 80 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName C4
SYMATTR Value 100n
SYMBOL res 624 432 M180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R8
SYMATTR Value 470
SYMBOL diode 880 96 R0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode 880 176 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL diode 880 256 R0
SYMATTR InstName D3
SYMATTR Value 1N4148
SYMBOL cap 832 48 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C5
SYMATTR Value 100n
SYMBOL cap 848 336 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C6
SYMATTR Value 100n
SYMBOL res 880 -48 R0
SYMATTR InstName R9
SYMATTR Value 6.8k
SYMBOL res 880 -144 R0
SYMATTR InstName R10
SYMATTR Value 3.9k
SYMBOL res 880 368 R0
SYMATTR InstName R11
SYMATTR Value 6.8k
SYMBOL res 880 464 R0
SYMATTR InstName R12
SYMATTR Value 3.3k
SYMBOL cap 1072 0 R0
SYMATTR InstName C7
SYMATTR Value 100n
SYMBOL cap 1072 352 R0
SYMATTR InstName C8
SYMATTR Value 100n
SYMBOL npn 1216 32 R0
SYMATTR InstName Q2
SYMATTR Value BC547B
SYMBOL pnp 1216 336 R0
SYMATTR InstName Q3
SYMATTR Value BC557B
SYMBOL res 1264 128 R0
SYMATTR InstName R13
SYMATTR Value 10
SYMBOL res 1264 224 R0
SYMATTR InstName R14
SYMATTR Value 10
SYMBOL res 1440 208 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R15
SYMATTR Value 18
SYMBOL res 1632 304 R0
SYMATTR InstName R16
SYMATTR Value 10k
SYMBOL cap 1552 144 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C9
SYMATTR Value 1u
SYMBOL cap 1552 240 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C10
SYMATTR Value 100n
SYMBOL res 1088 -144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R17
SYMATTR Value 33k
SYMBOL res 192 -96 R0
SYMATTR InstName R18
SYMATTR Value 470
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL pnp 576 272 M180
SYMATTR InstName Q1
SYMATTR Value BFT92
SYMATTR Prefix X
SYMBOL res -16 -160 M270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R19
SYMATTR Value 100
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap -16 -144 R0
SYMATTR InstName C11
SYMATTR Value 1u
SYMATTR SpiceLine V=10 Irms=10.541 Rser=0.004 Lser=0 mfg="KEMET"
pn="C0603C105K8PAC" type="X5R"
TEXT 872 -408 Left 2 !.ac lin 10000 10k 1g
TEXT 872 -376 Left 2 !.net V(Out) v2 Rout=50
TEXT 256 -312 Left 2 !.model BF256C NJF(Beta=1.4m Betatce=-.5 Rd=1
Rs=1 Lambda=4.6m Vto=-3.1\n+ Vtotc=-2.5m Is=33.57f Isr=322.4f N=1 Nr=2
Xti=3 Alpha=311.7u\n+ Vk=243.6 Cgd=2.132p M=.3622 Pb=1 Fc=.5
Cgs=2.104p Kf=23.06E-18\n+ Af=1)
TEXT 872 -448 Left 2 !.opt plotwinsize=0\n.opt numdgt=16
TEXT 1384 -664 Left 2 !* Filename: BFT92_SPICE.PRM\n* BFT92 SPICE
MODEL\n* PHILIPS SEMICONDUCTORS\n* Date : September 1995\n*\n* PACKAGE
: SOT23 DIE MODEL : BFT92\n* 1: COLLECTOR; 2: BASE; 3:
EMITTER;\n.SUBCKT BFT92 1 2 3\nQ1 6 5 7 7 BFT92\n* SOT23 parasitic
model\n Lb 4 5 .4n \n Le 7 8
.83n\n L1 2 4 .35n\n L2 1 6
.17n\n L3 3 8 .35n\n Ccb 4 6
71f\n Cbe 4 8 2f\n Cce 6 8 71f\n* PHILIPS
SEMICONDUCTORS Version:
2.0\n* Filename: BFT92.PRM
Date: July 1992\n*\n.MODEL BFT92 PNP\n+ IS =
4.37563E-016\n+ BF = 3.35815E+001\n+ NF =
1.00972E+000\n+ VAF = 2.33946E+001\n+ IKF =
9.95381E-002\n+ ISE = 8.70539E-014\n+ NE =
1.94395E+000\n+ BR = 4.94721E+000\n+ NR =
1.00254E+000\n+
VAR = 3.90385E+000\n+ IKR = 5.28157E-003\n+
ISC = 3.58864E-014\n+ NC = 1.39333E+000\n+ RB
= 5.00000E+000\n+ IRB = 1.00000E-006\n+ RBM =
5.00000E+000\n+ RE = 1.00000E+000\n+ RC =
1.00000E+001\n+ EG = 1.11000E+000\n+ XTI =
3.00000E+000\n+ CJE = 7.46659E-013\n+ VJE =
6.00000E-001\n+ MJE = 3.56829E-001\n+ TF =
1.74921E-011\n+ XTF = 1.35455E+000\n+ VTF =
1.55654E-001\n+ ITF = 1.00000E-003\n+ PTF =
4.50000E+001\n+ CJC = 9.37103E-013\n+ VJC =
3.96455E-001\n+ MJC = 1.99949E-001\n.ENDS
TEXT 264 -104 Left 3 ;Gets rid of negative\ninput resistance\nthat was
occuring\nabove ~ 1MHz
TEXT 480 -104 Left 3 ;Sets overall\ngain ~1
TEXT 1072 -88 Left 3 ;Sets output stage\noperating point\n~Vcc/2
TEXT 504 240 Left 3 ;Changed to\nPNP to\npreserve\noutput polarity
TEXT 1352 304 Left 3 ;Value changed\nfor more\naccurate\n50 ohm O/P
TEXT -112 -48 Left 3 ;No need for a\nridiculous\ndecoupling\n"Ghrismas
Tree"\nof capaciors.\nA (properly selected)\nsingle should be\nfine.
RECTANGLE Normal 384 96 128 -128 2
RECTANGLE Normal 560 32 400 -128 2
RECTANGLE Normal 1184 -48 944 -224 2
RECTANGLE Normal 704 304 496 176 2
RECTANGLE Normal 1456 384 1328 128 2
RECTANGLE Normal 112 96 -144 -208 2

[AC Analysis]
{
Npanes: 4
Active Pane: 3
{
traces: 1 {3,0,"(1+S22(v2))/(1-S22(v2))"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',1,0.7,0.1,1.7)
Y[1]: (' ',0,-32,4,16)
Log: 1 0 0
GridStyle: 1
PltMag: 1
Text: "" 1 (318761.751521045,1.75612244897959) ;Output VSWR 50 ohm
},
{
traces: 1 {5,0,"1/RE(Yin(v2))"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('_',1,1000,0,1e+009)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (331739.531535957,2053525026.45715) ;Parallel input
resistance
},
{
traces: 1 {2,0,"IM((Yin(v2)))/2/pi/freq"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('f',0,2.28e-013,3e-015,2.64e-013)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (337484.183978161,2.66207094420198e-013) ;Parallel
input capacitance
},
{
traces: 1 {524292,0,"V(out)"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',0,0.0794328234724281,2,1)
Y[1]: (' ',0,-240,30,90)
Log: 1 2 0
GridStyle: 1
PltMag: 1
PltPhi: 1 0
Text: "" 1 (341818.444827778,1.14101582205948) ;Gain
}
}
Click to expand...
 
On 3/1/2014 12:08 PM, amdx wrote:
HALT!
All the data I gave below will be in error, I found my 12 volt regulator
is defective. Probably for the reason given in the update.
Mikek
Click to expand...

False alarm. Note to self, always, always, reset variable knob on
scope attenuator to normal position.
Mikek
 
On Sat, 01 Mar 2014 13:11:06 -0600, amdx <nojunk@knology.net> wrote:

On 3/1/2014 12:08 PM, amdx wrote:
HALT!
All the data I gave below will be in error, I found my 12 volt regulator
is defective. Probably for the reason given in the update.
Mikek


False alarm. Note to self, always, always, reset variable knob on
scope attenuator to normal position.
Mikek
Click to expand...

That's alright Mikey, we've all done it ourselves O:)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On Sat, 01 Mar 2014 12:33:09 -0700, Jim Thompson wrote:

On Sat, 01 Mar 2014 13:11:06 -0600, amdx <nojunk@knology.net> wrote:

On 3/1/2014 12:08 PM, amdx wrote:
HALT!
All the data I gave below will be in error, I found my 12 volt regulator
is defective. Probably for the reason given in the update.
Mikek


False alarm. Note to self, always, always, reset variable knob on
scope attenuator to normal position.
Mikek

That's alright Mikey, we've all done it ourselves O:)
Click to expand...

There was a time when scopes had a light that came on to warn you that a
variable control was off "cal" position.

Usually a really tight detent, too.

Tek 7A13 can be tiresome. "Variable" knob pulls out, as well as turns,
but, when pulled out, limits the step attenuator knob rotation.
Unfamiliarity leads to breakage.

There's a switch, accessible through a hole in the side of the 7A13
module, that puts it into "near infinite impedance" mode. Great fun to
watch someone try to keep the trace on screen with nothing connected ;-)

--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On 3/2/2014 11:09 AM, Fred Abse wrote:
On Sat, 01 Mar 2014 12:33:09 -0700, Jim Thompson wrote:

On Sat, 01 Mar 2014 13:11:06 -0600, amdx <nojunk@knology.net> wrote:

On 3/1/2014 12:08 PM, amdx wrote:
HALT!
All the data I gave below will be in error, I found my 12 volt regulator
is defective. Probably for the reason given in the update.
Mikek


False alarm. Note to self, always, always, reset variable knob on
scope attenuator to normal position.
Mikek

That's alright Mikey, we've all done it ourselves O:)


There was a time when scopes had a light that came on to warn you that a
variable control was off "cal" position.
Click to expand...

I was comparing input to different stages for distortion. Roughly, I get
0.5vpp output from the FET before distortion, but can only bring the FET
output up to 0.3vpp before the second stage starts distorting.
Waiting for you all to suggest mods, without a complete redesign. :)
Used for the AM Broadcast Band, 500kHz to 1700kHz. Want vary high input
impedance, very low capacitance.
Mikek
 
On Sun, 02 Mar 2014 15:19:29 -0600, amdx wrote:

Want vary high input
impedance,
Click to expand...

You'll get that all right :)

On a more serious note, it's the use of a source follower that screws
things. You'll note that I redesigned with a unity-gain "drain follower".
Source, or emitter followers can have unforeseen consequences at high
frequencies.

Just rearrange the first stage, with an extra resistor, taking the output
from the drain. You don't have to make the second stage PNP, so long as
you don't mind the opposite output polarity.

The rest is just a matter of trimming values for unity overall gain, and
half-rail bias.

The LTspice schematic shows you how. Values may have to be adjusted in a
real-life circuit.

I ran the simulation with your 2N3904 - wipeout!

--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On 3/4/2014 1:26 PM, Fred Abse wrote:
On Sun, 02 Mar 2014 15:19:29 -0600, amdx wrote:

Want vary high input
impedance,

You'll get that all right :)

On a more serious note, it's the use of a source follower that screws
things. You'll note that I redesigned with a unity-gain "drain follower".
Source, or emitter followers can have unforeseen consequences at high
frequencies.

Just rearrange the first stage, with an extra resistor, taking the output
from the drain. You don't have to make the second stage PNP, so long as
you don't mind the opposite output polarity.

The rest is just a matter of trimming values for unity overall gain, and
half-rail bias.

The LTspice schematic shows you how. Values may have to be adjusted in a
real-life circuit.

I ran the simulation with your 2N3904 - wipeout!
Click to expand...

You'll need to walk me through this.
I truncated the file at,
SYMATTR SpiceLine V=10 Irms=10.541 Rser=0.004 Lser=0 mfg="KEMET"
pn="C0603C105K8PAC" type="X5R"
I then added this as a Spice directive.
Doesn't run.
I know I need to install the SUBCKT for the BFT92.
How do I do that?

2N3904 - wipeout! I suspect that is not good, could you define it a
little more?
If needed I can try to install the BFT92, but I don't know
if after my mod for the 2N3904 what that may involve. What do I need to
do to prevent it from oscillating with a new install.
Thanks, Mikek
 
On 3/4/2014 4:26 PM, amdx wrote:
On 3/4/2014 1:26 PM, Fred Abse wrote:
On Sun, 02 Mar 2014 15:19:29 -0600, amdx wrote:

Want vary high input
impedance,

You'll get that all right :)

On a more serious note, it's the use of a source follower that screws
things. You'll note that I redesigned with a unity-gain "drain follower".
Source, or emitter followers can have unforeseen consequences at high
frequencies.

Just rearrange the first stage, with an extra resistor, taking the output
from the drain. You don't have to make the second stage PNP, so long as
you don't mind the opposite output polarity.

The rest is just a matter of trimming values for unity overall gain, and
half-rail bias.

The LTspice schematic shows you how. Values may have to be adjusted in a
real-life circuit.

I ran the simulation with your 2N3904 - wipeout!


You'll need to walk me through this.
I truncated the file at,
SYMATTR SpiceLine V=10 Irms=10.541 Rser=0.004 Lser=0 mfg="KEMET"
pn="C0603C105K8PAC" type="X5R"
I then added this as a Spice directive.
Doesn't run.
I know I need to install the SUBCKT for the BFT92.
How do I do that?

2N3904 - wipeout! I suspect that is not good, could you define it a
little more?
If needed I can try to install the BFT92, but I don't know
if after my mod for the 2N3904 what that may involve. What do I need to
do to prevent it from oscillating with a new install.
Thanks, Mikek
Click to expand...

I'm into the bipolar .models file, but your model is not nothing like
the files I see, I don't know how much of the text to add.
Mikek
 
On 3/4/2014 4:41 PM, amdx wrote:
On 3/4/2014 4:26 PM, amdx wrote:
On 3/4/2014 1:26 PM, Fred Abse wrote:
On Sun, 02 Mar 2014 15:19:29 -0600, amdx wrote:

I ran the simulation with your 2N3904 - wipeout!


You'll need to walk me through this.
I truncated the file at,
SYMATTR SpiceLine V=10 Irms=10.541 Rser=0.004 Lser=0 mfg="KEMET"
pn="C0603C105K8PAC" type="X5R"
I then added this as a Spice directive.
Doesn't run.
I know I need to install the SUBCKT for the BFT92.
How do I do that?

2N3904 - wipeout! I suspect that is not good, could you define it a
little more?
If needed I can try to install the BFT92, but I don't know
if after my mod for the 2N3904 what that may involve. What do I need to
do to prevent it from oscillating with a new install.
Thanks, Mikek

I'm into the bipolar .models file, but your model is not nothing like
the files I see, I don't know how much of the text to add.
Mikek
Click to expand...

Added the subckt from filename to ends.
I get the error,
Unknown subcircuit called in:
xq1 n008 n014 n007 bft92
Mikek
 
On 3/4/2014 4:51 PM, amdx wrote:
> On 3/4/2014 4:41 PM, amdx wrote:

I finally got the file opened and run.
I went to the LTspice forum for help.
I see you ran it out to 1GHz, the design was for the 500kHz to 1700KHz,
but author said the original was good to 10MHz. Your changes make the
-3db point about 25Mhz.

What is the info after [AC Analysis] and how do I use it.
The file didn't run if I included it in the .asc file.

How do the changes alter the input impedance numbers.

Thanks, Mikek
 
On Wed, 05 Mar 2014 10:49:33 -0600, amdx wrote:

and how do I use it.
The file didn't run if I included it in the .asc file.
Click to expand...

That's the plot file.

Save it in the same directory as the .asc file, with the same name as the
..asc file and a .plt extension.

It defines the plots.


--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On Tue, 04 Mar 2014 16:41:20 -0600, amdx wrote:

I'm into the bipolar .models file, but your model is not nothing like
the files I see, I don't know how much of the text to add.
Click to expand...

It isn't a .model, it's a .subckt. Different thing. It includes package
parasitics.

If you've copied the file *exactly*, it should just run.

--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On Tue, 04 Mar 2014 16:51:55 -0600, amdx wrote:

Added the subckt from filename to ends.
I get the error,
Unknown subcircuit called in:
xq1 n008 n014 n007 bft92
Click to expand...

Are you actually using LTspice, or some other Spice?

The subcircuit is in the .asc file, should appear as a directive on the
schematic, and automatically be included in the netlist.

--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On Tue, 04 Mar 2014 16:26:06 -0600, amdx wrote:

I truncated the file at,
SYMATTR SpiceLine V=10 Irms=10.541 Rser=0.004 Lser=0 mfg="KEMET"
pn="C0603C105K8PAC" type="X5R"
I then added this as a Spice directive. Doesn't run.
I know I need to install the SUBCKT for the BFT92. How do I do that?

2N3904 - wipeout! I suspect that is not good, could you define it a little
more?
If needed I can try to install the BFT92, but I don't know
if after my mod for the 2N3904 what that may involve. What do I need to do
to prevent it from oscillating with a new install.
Click to expand...

Just open the supplied .asc file in LTspice, and plot using the supplied
..plt file. Nothing simpler.

RTFM.

You did turn off line wrapping, before copying the files, didn't you?
Split lines screw up LTspice.

The subcircuit is included in the .asc file. It should appear on the
schematic, and automatically be included.

The oscillation you got was due to parasitic L and C. Getting rid of the
"Christmas tree" of decoupling capacitors would be a good start. Bad
practice.

Wipeout - gain drops by 40dB at 500kHz. 2N3904 is not a suitable choice.


--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On Wed, 05 Mar 2014 10:49:33 -0600, amdx wrote:

I finally got the file opened and run.
I went to the LTspice forum for help.
I see you ran it out to 1GHz, the design was for the 500kHz to 1700KHz,
but author said the original was good to 10MHz. Your changes make the
-3db point about 25Mhz.
Click to expand...

It's always a good idea to run beyond design limits. That's how you find
out about stability problems. Phase margin, and all that...

500kHz to 1700kHz is a bit restrictive. Most, even ancient, Q meters go to
50MHz. My Marconi goes to 300MHz.

and how do I use it.
The file didn't run if I included it in the .asc file.
Click to expand...

Plot definitions file .It goes in the same directory as the .asc, but with
a .plt extension.

If your simulation is "foo.asc", call the plot file "foo.plt". If it's in
the same directory, it will automatically open when you run the
simulation, and display the intended plots.


> How do the changes alter the input impedance numbers.

Run the simulation with the supplied plot file in place, and the answer
will magically appear ;-)

--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
On Wed, 05 Mar 2014 12:14:35 -0800, Fred Abse wrote:

Run the simulation with the supplied plot file in place, and the answer
will magically appear ;-)
Click to expand...

Just noticed:

There's a mistake in the plot file, with respect to the output VSWR.

"(1+S22(v2))/(1-S22(v2))"

should be:

"(1+mag(S22(v2)))/(1-mag(S22(v2)))"

Sorry,my bad. I should have noticed, if I'd been awake!


Amended .plt file:

[AC Analysis]
{
Npanes: 4
{
traces: 1 {3,0,"(1+mag(S22(v2)))/(1-mag(S22(v2)))"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',2,0.96,0.08,1.84)
Y[1]: ('m',0,-0.001,0.0002,0.001)
Log: 1 0 0
GridStyle: 1
PltMag: 1
Text: "" 1 (311018.192820938,1.90984126984127) ;Output VSWR 50 ohm
},
{
traces: 1 {5,0,"1/RE(Yin(v2))"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('_',1,1000,0,1e+009)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (331739.531535957,2053525026.45715) ;Parallel input resistance
},
{
traces: 1 {2,0,"IM((Yin(v2)))/2/pi/freq"}
X: ('G',2,10000,0,1e+009)
Y[0]: ('f',0,2.28e-013,3e-015,2.64e-013)
Y[1]: ('m',1,-0.001,0.0002,0.001)
Log: 1 1 0
GridStyle: 1
PltMag: 1
Text: "" 1 (337484.183978161,2.66207094420198e-013) ;Parallel input capacitance
},
{
traces: 1 {524292,0,"V(out)"}
X: ('G',2,10000,0,1e+009)
Y[0]: (' ',0,0.0794328234724281,2,1)
Y[1]: (' ',0,-240,30,90)
Log: 1 2 0
GridStyle: 1
PltMag: 1
PltPhi: 1 0
Text: "" 1 (341818.444827778,1.14101582205948) ;Gain
}
}

--
"Design is the reverse of analysis"
(R.D. Middlebrook)
 
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