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Recent content by martinnl

  1. M

    Maximum output clock frequency in 0.35 µm

    When you say it suffers when driving a 20 MHz signal. What do you mean? Are the edges too slow? Doesn't it even reach full amplitude? A common mistake I see is that people expect the rise and fall time to be close to non existing but you should consider what you need in your application.
  2. M

    Do I need to re-entry the schematic when I work on a new technology?

    Since you use Virtuoso you can check a porting script done by Andrew Beckett. You have to define the device mapping and also be careful about callbacks. But bottom line is that it is a very crude porting, you can't really draw any conclusions about the process performance or be sure that the...
  3. M

    Difference between gm/id method and Vov design method

    I think one important aspect, perhaps not as important as the other mentioned but still, is that the gm/Id method is more direct. Both gm and Id directly describe something in the circuit compared to Vov which in itself doesn't really say much.
  4. M

    Current mirror in 2 stage op-amp

    The two mirrors does not have the same ratio 61 for the first one and 60 for the second one. Also the parasitic capacitance is different between the two. Also the operating point might be different. What kind of distortion do you see? Run a DC sweep where you sweep the input voltage and a...
  5. M

    Current mirror in 2 stage op-amp

    You don't give enough information for an actual answer but I can try and guess! With a 1:64 ratio you probably end up with either a large Veff or a large transistor. A large Veff results in distortions earlier. But without knowing sizes, type of distortion, operating points, some...
  6. M

    Analog and digital ground and supply voltage seperation in IC

    As much separation as you get in schematic, infinit, is not possible. What you can do is to separate them in a few different ways. If deep nwells are available you can use them or otherwise make low ohmic guard rings that pick up substrate noise so it does not propagate to the analog part...
  7. M

    Calculating output swing of amplifier

    Are you taking the vout1 from the gate of one of the pmos transistors in the differential pair?
  8. M

    Differential amplifier gain

    Okay then I understand where you got it from. The unit in this case is dBV, when you take 20log10(Volt) your unit is not dB but dBV. But I would stop earlier in the equation, you have A_noise, just find A_signal and you're done.
  9. M

    Differential amplifier gain

    Best way is probably to refer the noise back to the input and compare with the expected input signal. Since you have a certain gain your output signal depends on the input signal amplitude and your SNR will only be valid for a certain input/output amplitude. No need to run a transient. Run...
  10. M

    Differential amplifier gain

    And in dB 20log10(differential_gain)
  11. M

    Fast switching mechanism

    My reasoning was that it takes 3 ns to turn off and 3 ns to turn on and you don't want them to overlap. But if that is acceptable it would take 3 ns.
  12. M

    Fast switching mechanism

    The masw2000 datasheet specifies a Ton and Toff of 3 ns from 50% of the control signal to 10 or 90% of RF. This means, I assume, it takes 6 ns to switch over even with an infinitely fast driver. Also, when you say the inverter is to slow and you want it to output a -5 V signal from a FPGA...
  13. M

    Differential amplifier gain

    The differential input signal is the difference between the two inputs which in your case is 0. You only change the common mode level of the 0 amplitude input signal. Set two voltage sources to, for example, 0.5 V AC amplitude and whatever DC level you have. One should have 0 degrees phase and...
  14. M

    How can i simulate for im3 in ltspice?

    Some ideas: Reduce swing Increase supply All kind of negative feedback (source degeneration for example) Filtering input Without knowing your circuit and your requirements it's hard to give specific pointers.
  15. M

    Differential amplifier gain

    You apply the same signal on both inputs. What you see is your common mode gain.

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