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  1. LvW

    Integrator circuit using single resistor gain"ad620" op amp?

    Yes - of course. The ideal integrator function 1/jwT exhibits a magnitude drop of 20 dB/dec and a constant phase of -90 deg (+90 deg for an inverting integrator). However, a real intergator (based on a real opamp) has a phase characteristic which is near 90 deg and crosses the 90 deg at one...
  2. LvW

    Integrator circuit using single resistor gain"ad620" op amp?

    Integration means: Phase shift of 90 deg Therefore my question: Which accuracy do you require? More than that, the data sheet contains no information about the gain of 1E4 (frequency response, slew rate).
  3. LvW

    Integrator circuit using single resistor gain"ad620" op amp?

    1.) The frequency response of an (ideal) integrator is not constant but drops with 20dB/dec. 2.) For good integration prperties the open-loop gain of the used amplifier should be as large as possible (opamp: 1E5...1E6). In your case - with a fixed gain of max. 10000 - the "intergrator" will...
  4. LvW

    phase shift in filter

    Each filter is realized with components that have frequency-dependent proprties (L and or C). The frequency-dependent resistance of these parts is connected with corresponding phase shifts. This cannot be avoided because it is a basic property of the parts. As a consequence - also filters have...
  5. LvW

    Why does a current source on the collector of a BJT bring kaboons of gain ?

    Ic will change as usual as a function of Vbe. However, because of the constant current source in the collector path the change is forwarded to the next stage. That is the core of the working principle. Remember - Ic is split into two other currents: One current into (or out of) the current...
  6. LvW

    Why does a current source on the collector of a BJT bring kaboons of gain ?

    Yes - Ehsan is referring to typical amplifiers that consists of several stages - for example opamps. When only moderate gains are required and no further stages are necessary and - in most cases - ohmic resistors in the collector path are sufficient. However, for large gain values (opamps) with...
  7. LvW

    Why does a current source on the collector of a BJT bring kaboons of gain ?

    The most simple answer is: Such an (active) current source presents a very large internal ac resistance (and at the same time a moderate and finite dc resistance). Thus, it is very advantageous to replace the ohmic collector resistance by such a current source. This allows large gain values...
  8. LvW

    Series pass voltage regulator not working as expected

    "better amplifier" means: Much more gain. Thus, the sensitivity to error voltages is considerably improved. However, watch the stability properties because larger loop gain reduces the phase margin.
  9. LvW

    Op amp power supply help

    Adam - yes, perhaps there was a misunderstanding between us because your comment was below your Fig. 3. But now I understand what you mean. Sorry.
  10. LvW

    Op amp power supply help

    Question: What means "virtual ground"? Answer: When the non-inv. input is grounded and negative feedback causes the inverting input to have approximately (virtual) the same potential. Because grounding of the non-inv. input - for "normal" linear operation - is done for split supply only, the...
  11. LvW

    Op Amps - non-inverting

    Jason, before starting to solve the task you have to be informed about the meaning of the various mentioned parameters (Aol, IIB, Iio, SR, compensared/uncompensated). Are you?
  12. LvW

    PSpice does not work anymore

    Steve, thank you very much for all these tips. I will try to follow these steps during the weekend. By the way - it´s not a big problem because I can run the program on a spare computer (rather slowly, but it works). More than that, I can work with another simulation package on the main computer...
  13. LvW

    PSpice does not work anymore

    Yes - you are right. I should have been more specific. It is the schematic entry feature ("schematics") that does not start anymore. However, it is possible to start the simulator PSpice which needs a written circuit file.
  14. LvW

    PSpice does not work anymore

    Just for clarification: I never have mentioned Win 7 in my postings. It´s still XP (on a separate machine not for internet use). System restore didn´t work. Answer: It was not possible to restore your system to ... (date).
  15. LvW

    PSpice does not work anymore

    Steve - thank you for replying. I have forgotten to mention that * I work with PSpice/Schematics ver. 9.2 * Reinstalling the program did not help at all. Regarding your question: Reinstalling was possible only in the safe mode for Windows. In normal mode there was absolutely no reaction upon...
  16. LvW

    PSpice does not work anymore

    Hello to all, until yesterday I have worked with PSpice (Schematics), vers. 9.2, without problems (Windows XP - 32). However, suddenly the program does not start anymore. I am sure that I have not installed anything new on the computer. Then I`ve tried the safe modus of windows and - yes - in...
  17. LvW

    Op amp power supply help

    Just a small - but important - supplement (to avoid misunderstandings on beginner´s side): "When used as an amplifier" with negative feedback, "both inputs....."
  18. LvW

    Physics of n-p Junction in a diode

    Quote: "...explain the physics of how a microscopic physical width change can influence the current". One last sentence from my side: I think, a "microscopic change" of a microscopic dimension can be remarkable. (By the way: If I remember well, it is the change of the BJT`s depletion layer that...
  19. LvW

    Physics of n-p Junction in a diode

    Your "..proposition is similar to the wrong belief that the base current of a BJT controls the collector current. The base current is an indicator of the collector current, not the cause." Ratch - you may remember that I am with you regarding this question. Hence, I do not understand the...
  20. LvW

    Physics of n-p Junction in a diode

    "Neither is first or last. They both change together." Ratch - only this last sentence meets the core of my question. All other statements/explanations are known to me. When they "change together" would it really be wrong to say that the "collector current is controlled by the width of the...
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