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input and output noise simulation with Spectre Noise analysis?

isazulkc
Hi, I would like to know if the output noise (V-rms) obtained when I simulate the output noise of a circuit with Spectre simulator (Noise) include the noise of ALL the components referred to the output ? In fact I got some inconsistant result when comparing the input and output noise (V-rms) given by the simulator. I got 1.4 mV-rms at the output while I have 13 mV-rms as input refered noise. I know input referred noise give the input equivalent noise (anasimhelp) considering a noise-free circuit, but I am note sure for the output noise. Thanks for your help!! Best regards
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  • Lancehp

    Hi Andrew,

    I know this is an old thread but just wanted to give it a shot. For some of us that don't have access to the ADE in cadence, can you please elucidate how to write the code to do noise analysis in spectre. So for example i have a TIA (inverter with resistor feedback) driven by an ideal current source to model the reversed biased diode current, if i wanted to do a noise analysis as a function of frequency to computer the input referred noise current, do i insert an "iprobe" at the input between the ideal current source and gate of the inverter? And how exactly do i set instance parameter isnoisy=no for the feedback resistor for example. say my netlist looks like this for example (used spice syntax for device definitions)

    Mn out in1 VSS VSS

    Mp out in1 VDD VDD

    Rfb out in1 300

    //current source

    Idriver int VSS 10u

    ip (int  in1) iprobe

    //Question 1

    Did i specify the iprobe correctly?

    //Question 2

    How do i specify noise analysis to be included in my AC frequency sweep  (I am not using ADE, purely spectre netlist)

    //Question 3

    How do i specify not to include the noise contribution of the resistor feedback Rfb using isnoisy=no ?


    If i need to use pnoise analysis please address the questions similarly.

    Thanks!

Reply
  • Lancehp

    Hi Andrew,

    I know this is an old thread but just wanted to give it a shot. For some of us that don't have access to the ADE in cadence, can you please elucidate how to write the code to do noise analysis in spectre. So for example i have a TIA (inverter with resistor feedback) driven by an ideal current source to model the reversed biased diode current, if i wanted to do a noise analysis as a function of frequency to computer the input referred noise current, do i insert an "iprobe" at the input between the ideal current source and gate of the inverter? And how exactly do i set instance parameter isnoisy=no for the feedback resistor for example. say my netlist looks like this for example (used spice syntax for device definitions)

    Mn out in1 VSS VSS

    Mp out in1 VDD VDD

    Rfb out in1 300

    //current source

    Idriver int VSS 10u

    ip (int  in1) iprobe

    //Question 1

    Did i specify the iprobe correctly?

    //Question 2

    How do i specify noise analysis to be included in my AC frequency sweep  (I am not using ADE, purely spectre netlist)

    //Question 3

    How do i specify not to include the noise contribution of the resistor feedback Rfb using isnoisy=no ?


    If i need to use pnoise analysis please address the questions similarly.

    Thanks!

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