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Type: Posts; User: frankrose

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  1. Replies
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    Closed: Re: W/L of pMOS and nMOS of CD4007 Chip.

    Be cautious about the multiplier and finger number in the SPICE model, probably one of them is =2 for both the NMOS and PMOS. Then the total width is about twice of the mentioned values in the last...
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    Closed: Re: W/L of pMOS and nMOS of CD4007 Chip.

    Hard to answer, probably nobody knows the technology, normally it is confidental.
    However, the TI was very nice, in the datasheet they show the exact layout and schematic, with dimensions. ...
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    Closed: Re: CMRR at different closed loop gain

    Feedback of fully differential amplifier should improve the CMRR I guess (assuming perfect resistor matching...).
    But even without feedback the fully diff. OPAmps have great CMRR usually. This is...
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    Closed: Re: CMRR at different closed loop gain

    Datasheets are written by different engineers from different countries, not everybody is thinking on the same way, sometimes they make mistakes too when they write the datasheet (in many cases not...
  5. Closed: Re: How to differentiate offset voltage error from CMRR and PSRR

    I don't think it is totally zero, you are right, but this is the practical way. There you can assume its effect is minor compared to mismatch.
    And CMRR at DC should be negligible, if you want to...
  6. Closed: Re: How to differentiate offset voltage error from CMRR and PSRR

    With typical or nominal supply voltage the PSRR caused offset is 0V, and in the middle of the common mode voltage range the CMRR caused offset is also 0V. The offset from mismatch should be measured...
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    Closed: Re: Sooch current mirror

    This is not really true. When I designed high swing mirror none of the transistors were in triode region, over PVT corners. I didn't use stacked diodes to bias cascode transistors. Point of this wide...
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    Closed: Re: Sooch current mirror

    That current is negligible I think, you should find another reason(s). Area, cost, linearity, operation range, mismatch, maybe share these results with true comparison.


    Why not used another...
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    Closed: Re: Sooch current mirror

    I don't have experience with it, but think about these:
    a, Hand calculations are not so effective, they won't tell you how it handles process/supply/temperature variation. Run simulation.
    b, How...
  10. Closed: Re: How should be Pin1dB less or more compared with Pout1dB?

    Sorry, what? I am not sure I understand the questions. Ideally input/output compression is infinite I guess. And Pout.dB=Pin.dB+Gain.dB . So same is true for input/output compression points.
  11. Closed: Re: Why an input inductor required in all GPS LNA?

    Chip designers could implement a 50 Ohm input by a bias resistor, common-gate amplifier's input transconductance, etc. But this way is a waste of sensitivity or/and power.
    Discrete inductance is...
  12. Closed: Re: Magnitude function analog circuit (square root of sum of two squares)

    Not enough to multiply the I branch with the Q branch signal? The multiplied output's DC level should be rational with the I and Q magnitudes. RSSI operates this way usually.
    Tell us more about the...
  13. 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.
  15. 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...
  16. 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...
  17. 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?
  19. 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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