Forums

For amdx: - Kleijer amplifier reworked.

Started by Fred Abse February 28, 2014
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.
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 > } > } > >
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: >
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 >> } >> } >> >> >
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
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:-) ...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:-)
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.
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,
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! >
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