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Type: Posts; User: frankrose

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  1. Closed: Re: LTspice Wolfspeed mosfet model doesn't seem to be working

    Connect disconnected pins too (Tj Tc). Don't let them floating. I see 2.4A if they are grounded.
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    Closed: Re: LNA circuit not working

    Hmm... nice curves....
    If it is an IC LNA be cautious with the output termination, it is not necessary to use 50 Ohm resistor.
  3. Closed: Re: High power efficiency oscillator topologies?

    So, you say Cprobe changes from 6pF to 18pF. That means the maximum/minimum C ratio is =18/6=3.
    The LC oscillators regularly have a square root function dependence on L or C values, and...
  4. Closed: Re: High power efficiency oscillator topologies?

    Amplitude depends on capacitance (and inductance) ratios too, you have play with them. Or on bias, you have set almost half of the supply voltage on Q2 emitter, wasted the supply voltage a bit. Hard...
  5. Closed: Re: High power efficiency oscillator topologies?

    Cascode topology is basically reduce output swing, and above circuit only use cascode transistor to save DC current of a 2nd stage, it works as common-emitter amplifier from AC standpoint by C1 and...
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    Closed: Re: LNA circuit not working

    ....noise analysis?
  7. Closed: Re: Motor current calculation using current sensor

    I recommend to look at the output waveform of the sensor with an oscilloscope. The sensor can handle quite wide bandwidth (120kHz), not too hard to imagine that the switching caused it. Or try to add...
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    Closed: Re: Transmission Zeroes in Bandpass Filters

    Hi,
    Could you share whichs bands are you interested in and/or what is the target (combine RX and TX, or connect antennas together or reject a band between 2 other)? Maybe there are better solutions,...
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    Closed: Re: LNA circuit not working

    Great! I am sure it helped a lot, however you still run transient analysis. Run AC to find the resonance frequency, with 2.25GHz and transient analysis you won't excite the LC tank on the exact...
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    Closed: Re: LNA circuit not working

    You have nanoamper operating drain current. You are far from matching problems. Simply your bandwidth is much lower than the LC resonance frequency. Nobody ever designed a GHz amplifier with nA or...
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    Closed: Re: LNA circuit not working

    Where did you hear about that high L generates positive gain? Gm will decrease with higher L, parasitics will increase.
    Why don't you run AC analysis rather to get information about gain?
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    Closed: Re: Mosfet Gate ringing and overheat

    It is heated becasue it dissipates power, I guess the drain current multiplied with the drain-source voltage is not zero for a transition period.
    Ringing can cause by inductance at the gate or...
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    Closed: Re: LNA circuit not working

    You are using 1GHz input, and a 2.2GHz resonant LC tank. Hmm... what could be the problem? And yes, C3 makes no sense, 16Ohm at 1GHz, Lbias is like 6Ohm, W of your devices is too small, L is too big,...
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    Closed: Re: HSPICE BJT simulation error

    I guess some BJT parameters in your model is not included, and HSpice uses different default values as ADS when a parameter is missing. I would check default values of simulators (especially where...
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    Closed: Re: Applications I can work On

    4) motorized toilet brush. It would be more effective I guess.
    5) motorized curtain. Not interesting, just practical.
    6) motorized door closer. Nobody has to lie anymore that it was done.
    7)...
  16. Closed: Re: How Device Resistance change with respect to W and L in any technoogy

    On you figure the sheet resistance is 330 Ohm, you set 2kOhm for the desired value with 2um desired width. Cadence will calculate the necessary length from these parameters by a function like this:
    ...
  17. Closed: Re: Why is pmos and nmos put vertically and not side by side(horizontally)in ic layou

    planar IC fabrication is "side by side", vertical MOS channels are not existing or at least not conventional, I have never saw it. Or what do you mean under they are put vertically?
    Go through a...
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    Closed: Re: NMOS LDO current sense circuit help

    I think you could try these things:
    a, add calibration to balance the error of the current mirror. It is reliable, many ways you can implement it, some example:
    - analog: potentiometer instead of...
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    Closed: Re: NMOS LDO current sense circuit help

    I think you have too much gain in the current control loop, and if the speed of the control loop is comparable with the settling speed of the main LDO feedback system, than it can cause unstability...
  20. Closed: Re: Different connections to Common node in differential pair

    yes, scenario 3, sorry for the typo.
    I think it is reasonable when VDD is about a Vgs+Vdsat=Vth+2×Vdsat. This is the minimum VDD for an active current-mirror loaded quasi-differential pair.
    Vth...
  21. Closed: Re: Different connections to Common node in differential pair

    1. use to improve linearity. it is an easy way, low cost, and possible to implement degeneration without high common mode reduction if you use 2 tail current sources for Q1 and Q2, and the...
  22. Closed: Re: How to build a oscillator by using a Sallen Key filter.

    Just an other way to get sine wave is to add low-pass filter stages to the output to remove harmonics from the distorted signal.
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    Closed: Re: TSMC 65nm mocap_rf varactor

    Everything should be described in the PDK (Process Design Kit) documents, don't you have those .pdf files? Place one in your schematic and check its properties (press Q), maybe it is described there.
  24. Closed: Re: How to build current source based on modified Hawland current pump for 150 mA?

    By the equation from you (I didn't check) if you set R5=R4-R2 it should handle the load dependence.
    I think your input source at Vin has a varying internal resistance maybe. How you generate Vin?
  25. Closed: Re: CMRR is less than the DC differential gain

    2 possible reasons:
    a, you have big common mode gain because CMRR(dB) = Ad(dB) - Acm(dB)
    b, you do something wrong
    Check signs, expressions in calculator, the testbench itself.
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