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  1. LvW

    Effects of feedback

    ....or try to find out by yourself (after learning about negative feedback) WHY positive feedback is generally undesirable.
  2. LvW

    Bandpass filter help

    OK - let`s designate the grounded 680 Ohm as R2 (R1 and R5 as before). Again, we can set C1=C2=C * R5=2Q/(wc*C) * 4Q^2=R5[(1/R2) + (1/R1)] Thus, you can select a value for C as well as for R1 or R2.
  3. LvW

    Effects of feedback

    At first, you have to ask yourself: Whar are the most important parameters determining the properties of the amplifier? And - as a second step - you can try to find out which of these parameters could be influenced by negative feedback.
  4. LvW

    Bandpass filter help

    Sorry - but I have to apologize. I have overlooked the 680 ohm resistor because in most cases this resistor is set to infinity and all the formulas I have given apply to such a design only. For a finite value other formulas apply. Are you still intersted in a revised set of formulas?
  5. LvW

    Bandpass filter help

    As far as I understand your problem you ask how to design the bandpass stages. OK? Here is a basic set of formulas (original: R1=1k, R5=560k) assuming two identical cacpacitors C: * Select two equal capacitors suitable for the desired center frequency * Center angular frequency...
  6. LvW

    LVDT circuit - need to explain how it works

    Yes - good recommendation. As an alternative, you could search for "Integrator-oscillator" .
  7. LvW

    NPN BJT Transistor Biasing problem

    "You can not have everything you want" In electronicss, there is one general problem: Everything is a trade-off. That means: Improving one parameter is connected with a degradation of another parameter. In your case: The "best" signal swing at the output exists without any DC stabilization...
  8. LvW

    Obtain transfer function using KVL

    It is nearly impossible to read and check your "equations". I only can guess that your "z" is the same quantitty as the "Z" in the reference (page 3): Impedance at the node in the middle of the circuit, correct? In this case, your eqation (z = 1/sC x sL / 1/sC + sL) looks like a parallel...
  9. LvW

    non inverting amplifier

    I like to be a bit more detailed (only the middle part of my former answer) : With 1/Ao<< Hfb and 1/Hfb=(1+R2/R1) we arrive (after suitable re-arranging) at Acl=(1+R2/R1)[1/(1+s/(wo*Ao*Hfb))] The first part is the IDEAL closed-loop gain Acl(ideal)=(1+R2/R1) and the second part (expression in...
  10. LvW

    non inverting amplifier

    This answer concerns the relation between gain and bandwidth for a non-inverting opamp-based amplifier: In most cases, we can use a first order lowpass function for the real frequency dependence of the open-loop gain: Aol=Ao/[1+s/wo] Thus, based on the expression for the closed-loop gain...
  11. LvW

    Design 2 stage amplifier

    Any question? Did you consult the data sheet for the "OPA 551 current amplifier"?
  12. LvW

    Obtain transfer function using KVL

    I think, we can say that the voltage divider rule is based on KVL. Hence, applying this rule twice (at the node in the middle and at the output) the problem can be solved using KVL. .
  13. LvW

    non inverting amplifier

    What do you expect for 2mV input and a gain of 1500?
  14. LvW

    help me quickly: diode curves question

    In the future, I will do my very best to follow the guide lines.
  15. LvW

    help me quickly: diode curves question

    Kris - sorry, if I have explained too much. On the other hand, was it really remarkable more detailed than your answer? (.. it has a characteristic called "small-signal resistance", also called "incremental resistance", "dynamic resistance" and "AC resistance".)
  16. LvW

    help me quickly: diode curves question

    For each part having a non-linear current-voltage characteristics you must discriminate between STATIC and DYNAMIC resistance. The static resistance is simply the ratio of DC values (Rst=V/I for a certain operating point) and the dynamic (differential) resistance is r,dyn=v/i. As mentioned...
  17. LvW

    help me about slew rate

    It seems the questioner is not interested anymore.
  18. LvW

    help me about slew rate

    OK - thus, we derive some information from measurements resp. simulations, right? However, why at the unity gain frequency (with/without feedback)? In case, we are allowed to derive the slew rate from experiments (and not from the given data only) - why not using the definition for the slew...
  19. LvW

    PLL /VCO simulation

    As far as PLL simulation is concerned, I have made very good experiences with VISSIM (from Visual Solutions Inc.). But, of course, it depends if you want to simulate on parts level or on block level.
  20. LvW

    help me about slew rate

    All opamp parameters shown in the table are linear small-signal parameters. However, the slew rate is a large-signal parameter (non-linear) - hence, it is not possible to derive any information on slewing properties from these data. In particular, for an approximate theoretical calculation of...
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