[Qucs-help] Convergance failure

[Alistair H. <Ali...@xt...>]

Hi

No matter what I try I cannot get a solution out of the following circuit, I have tried using various solvers and op-amp models (including the 471) without success.

The circuit works very well in reality with an LT1366 as the op-amp and simulates correctly in LTspice

The correct value of out.V = -1.0V

Can anyone get this to simulate properly in QUCS, Thanks

Alistair

<Qucs Schematic 0.0.15>
<Properties>
  <View=0,151,1215,999,1,137,0>
  <Grid=10,10,1>
  <DataSet=data_vctrl1.dat>
  <DataDisplay=data_vctrl1.dpl>
  <OpenDisplay=1>
  <showFrame=0>
  <FrameText0=Title>
  <FrameText1=Drawn By:>
  <FrameText2=Date:>
  <FrameText3=Revision:>
</Properties>
<Symbol>
</Symbol>
<Components>
  <Vdc V2 1 730 780 18 -26 0 1 "-12" 1>
  <Vdc V1 1 270 510 18 -26 0 1 "0.21" 1>
  <GND * 1 270 540 0 0 0 0>
  <GND * 1 730 810 0 0 0 0>
  <Vdc V3 1 950 380 18 -26 0 1 "3.3" 1>
  <R R5 1 870 340 -26 15 0 0 "470" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
  <GND * 1 950 410 0 0 0 0>
  <R R3 1 650 670 15 -26 0 1 "2670" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
  <R R4 1 800 520 15 -26 0 1 "27" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
  <.DC DC1 1 210 710 0 43 0 0 "26.85" 0 "0.001" 0 "1 pA" 0 "1 uV" 0 "no" 0 "150" 0 "no" 0 "LineSearch" 0 "CroutLU" 0>
  <_BJT Q2N2907A_1 1 800 600 8 -26 1 0 "pnp" 0 "3.81e-13" 0 "1" 0 "1" 0 "0.14" 0 "0.21" 0 "139" 0 "20" 0 "1.53e-11" 0 "2" 0 "0" 0 "2" 0 "154" 0 "4" 0 "0" 0 "0" 0 "0.221" 0 "0.552" 0 "2.21" 0 "1.56e-11" 0 "0.75" 0 "0.33" 0 "2.08e-11" 0 "0.75" 0 "0.33" 0 "1" 0 "0" 0 "0.75" 0 "0" 0 "0.5" 0 "6.36e-10" 0 "0" 0 "0" 0 "0" 0 "6.37e-08" 0 "26.85" 0 "0" 0 "1" 0 "1" 0 "0" 0 "1" 0 "1" 0 "0" 0 "1.5" 0 "3" 0 "1.11" 0 "26.85" 0 "1" 0>
  <GND * 1 500 420 0 0 0 3>
  <Diode D_1N4148_2 1 650 540 -109 -26 1 1 "222p" 1 "1.65" 1 "4p" 0 "0.333" 0 "0.7" 0 "0.5" 0 "0" 0 "0" 0 "2" 0 "68.6m" 0 "5.76n" 0 "0" 0 "0" 0 "1" 0 "1" 0 "75" 0 "1u" 0 "26.85" 0 "3.0" 0 "1.11" 0 "0.0" 0 "0.0" 0 "0.0" 0 "0.0" 0 "0.0" 0 "0.0" 0 "26.85" 0 "1.0" 0 "normal" 0>
  <OpAmp OP1 1 550 440 -26 42 0 0 "1e6" 1 "15 V" 0>
  <Diode D_1N4148_1 1 710 440 -26 13 1 2 "222p" 1 "1.65" 1 "4p" 0 "0.333" 0 "0.7" 0 "0.5" 0 "0" 0 "0" 0 "2" 0 "68.6m" 0 "5.76n" 0 "0" 0 "0" 0 "1" 0 "1" 0 "75" 0 "1u" 0 "26.85" 0 "3.0" 0 "1.11" 0 "0.0" 0 "0.0" 0 "0.0" 0 "0.0" 0 "0.0" 0 "0.0" 0 "26.85" 0 "1.0" 0 "normal" 0>
  <R R1 1 400 460 -26 15 0 0 "10000" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
  <R R2 1 560 310 -26 15 0 0 "46500" 1 "26.85" 0 "0.0" 0 "0.0" 0 "26.85" 0 "european" 0>
</Components>
<Wires>
  <650 440 650 510 "" 0 0 0 "">
  <650 570 650 600 "" 0 0 0 "">
  <800 440 800 490 "" 0 0 0 "">
  <800 550 800 570 "" 0 0 0 "">
  <650 600 650 640 "" 0 0 0 "">
  <650 600 770 600 "" 0 0 0 "">
  <650 700 650 720 "" 0 0 0 "">
  <650 720 730 720 "" 0 0 0 "">
  <800 630 800 720 "" 0 0 0 "">
  <800 340 800 440 "" 0 0 0 "">
  <730 720 800 720 "" 0 0 0 "">
  <730 720 730 750 "" 0 0 0 "">
  <270 460 270 480 "" 0 0 0 "">
  <270 460 370 460 "" 0 0 0 "">
  <430 460 470 460 "" 0 0 0 "">
  <800 340 840 340 "" 0 0 0 "">
  <900 340 950 340 "" 0 0 0 "">
  <950 340 950 350 "" 0 0 0 "">
  <590 310 590 340 "" 0 0 0 "">
  <590 340 800 340 "out" 790 310 165 "">
  <470 310 470 460 "" 0 0 0 "">
  <470 310 530 310 "" 0 0 0 "">
  <590 440 650 440 "oa" 670 410 48 "">
  <500 420 520 420 "" 0 0 0 "">
  <470 460 520 460 "" 0 0 0 "">
  <650 440 680 440 "" 0 0 0 "">
  <740 440 800 440 "" 0 0 0 "">
</Wires>
<Diagrams>
</Diagrams>
<Paintings>
</Paintings>




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