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Type: Posts; User: rmanalo

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  1. Closed: How to verify MOSFET resistance implemented as a nulling resistor in an OpAmp

    Hello everyone,

    I'd like to verify the MOSFET's resistance (Rz) in an opamp. showin in the figure.

    153024

    Usually I see this in an operating point simulation where I simply measure the...
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    Closed: Re: Transient measurements in HSPICE

    Thank you for your help.

    here is the output.
    152987

    Interestingly it is similar to that of the previous. The accuracy however did not change and still got around 82 nVpp corresponding to a...
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    Closed: Re: Transient measurements in HSPICE

    I don't know how to implement 244.5 mV via VCVS. Is it something like:



    E1 Vout gnd Vr gnd -1 $where Vr is 244.5 mV? because if so, then why not use Vr directly?


    I did however made an...
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    Closed: Re: Transient measurements in HSPICE

    It's for verification. I was tasked to show that AC analysis and transient simulations matched with regards to PSRR.

    - - - Updated - - -



    Thank you for your input. If my understanding is...
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    Closed: Re: Transient measurements in HSPICE

    Only .option post

    I did looked into increasing accuracy from the HSPICE Manual and added a few additional commands.



    .option ABSVDC=1e-12
    .option ABSTOL=1e-12
    .option ABSI=1e-12
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    Closed: Re: Constant-gm bias circuit

    If I made any mistakes, please point them out. Thanks.

    152874
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    Closed: Re: Constant-gm bias circuit

    I got a different answer, maybe I made a mistake in the derivation but you can check to see if it's right though.
    152866

    edit:
    Oh I see my mistake now, when I absorbed (W/L)4c into the square...
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    Closed: Transient measurements in HSPICE

    Hello everyone,

    I recently designed a high PSRR voltage reference circuit with a self-regulating feedback network. I then derived the transfer function from supply to output and I got my...
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    Closed: Re: PMOS input Folded Cascode 0.35µm

    For general analog design, the L used is typically 2-3 times the minimum length. This choice is a good trade-off between speed and gain.



    If you read baker's book, there's a modeling procedure...
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    Closed: Re: feel of diffrential equations for Novice

    That's basically the entire premise of Advanced Engineering Mathematics. You can ready any book on this, specifically on DEs with boundary conditions.
  11. Closed: Re: Algebraic System Response Equation into Circuit Design

    Opamps perform arithmitic operations on signals. Gilbert cells perform multiplication. and the combination of the two performs division. analog.com
  12. Closed: PSRR Considerations for high speed applications

    Hello everyone,

    So far in my studies I have analyzed and designed voltage references through simulations. I've read articles where the PSRR of most reference circuits are tested from 10 Hz to 10...
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    Closed: Re: Diode connected load or current mirror

    It's a PMOS current source. their difference is their equivalent impedances. the diode connected load is simpler but it's small signal resistance is 1/gm (low impedance node) while for the one with a...
  14. [SOLVED]Closed: Re: Settling time simulation for the operational amplifier in Cadence

    In Baker's book, CMOS Circuit Design, Layout, and Simulation 3rd ed. pp. 787, for testing he used a 5mV step input signal to avoid slew rate limitations.
  15. Closed: Re: Output of OTA with capacitor or without capacitor

    Hello,
    Isn't simulating without capacitors and resistors is testing the the OTA in no load conditions? I think this is done as a laboratory experiment to see the behavior of an OTA. Moreover,...
  16. Closed: Re: Deaign of low ON resistor CMOS transmission gate

    Yes I do realize that the specs achieved are process dependent. But I was wondering if there's a circuit technique involved in obtaining a relatively flat on resistance and not rely on sizing and...
  17. Closed: Re: Deaign of low ON resistor CMOS transmission gate

    I think you can design the on resistances of S1, S2, and S3 to be equal in this case. (i.e. Vo2/Vi2=-RS3/RS2)



    I'd like your opinion on how industry designed switches are made. Some have very...
  18. Closed: Re: How to find formula of calculating resistance in Pcell?

    Is PCell similar to instance calls (i.e. M1, M2, ... M#) in HSPICE?
    Resistance is calculated as R=(L/W)*Rsquare where Rsquare is found in the model file as Rsh.
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    Closed: Re: MOSFET diode connected for biasing

    In my opinion set up (2) is more precise. You'll notice that in set up (1) you set the biasing by increments of Vgs for each transistor stacked. While in set up (2) the two transistors can be seen as...
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    Closed: Re: Current in bulk cascode device

    Recall that the bulk of an NMOS is always connected to the lowest potential because we don't want the parasitic PN diodes to turn on. Now because the cascode device is at a higher potential, the...
  21. [SOLVED]Closed: Re: CMOS device characterization of Vth [Ref: CMOS Analog Circuit Design - Holberg]

    Most of the time I use the vth listed in operating point analysis in HSPICE. I was interested in how different textbooks have different parameter extraction procedures. For example in baker's book,...
  22. [SOLVED]Closed: Re: CMOS device characterization of Vth [Ref: CMOS Analog Circuit Design - Holberg]

    hello @ t4_v, in the appendix the procedure involved a "linear regression" using data points, i.e. the use of numerical methods as shown in the image below,

    152168

    for the extrapolation of Vth,...
  23. [SOLVED]Closed: CMOS device characterization of Vth [Ref: CMOS Analog Circuit Design - Holberg]

    Hello everyone,

    I'd like your opinion on the parameter extraction of the threshold voltage used for hand calculation, please see the snipped image from the book and simulated graph (L=5um for a...
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    [SOLVED]Closed: Re: Load Conditions of an Opamp

    Thank you for the link @vivekroy. Your comments are noted, I attached the citation of the paper for future reference of this thread.

    [ref] L. Zuo, S.K. I/s/l/a/m/, "Low-voltage bulk-driven...
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    [SOLVED]Closed: Re: Load Conditions of an Opamp

    Thank you for the reply @crutschow, I'd like to know what is their significance, like for example does that mean it's the maximum input capacitance of a PMOS pass transistor of an LDO? or the...
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