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    Adding a pulsed switch to a dc voltage source in cadence library

    i want to add a switch for creating a pulsed output with a certain frequency. I know that the voltage source could be pulsed but i need to keep it on a certain dc voltage and the switch will just have to follow this voltage. does anyone have an idea which component in cadence lib would achieve that? Thanks

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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    H,

    this is about no usable information.

    Try to give values with units. At least a range from min to max...
    and/or (hand drawn) circuits, waveforms with units, flow charts...

    Please understand that informations like "certain frequency", "voltage source could be pulsed", "certain DC level" ... are abslolutely useless

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    i just need to simulate a 50MHz pulse by using a 3.3V DC voltage source, and i want to use a switch for that because the dc voltage is changing and i want the clock to follow the max voltage of the circuit



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    You can either use a CMOS inverter supplied by the varying voltage or a SPDT switch (complementary switching SW components).



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    is there such a switch in cadence? i don't want to use MOSFETs as they are temperature dependant i would prefer using an ideal switch in that case



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    is there such a switch in cadence?
    Cadence is a tool vendor, the simulator is Spectre. There is an ideal switch SW in SPICE and Spectre And there is a manual named Spectre Circuit Simulator Reference. Another option is a behavioral voltage source (B component).



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    i have in cadence a library called cadencelib which i'm using for simulating ideal components i guess it comes with cadence and that's the one i wanted to use



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    It seems you try to do simple thing in very complicated way.
    Describe once again what you would like to achieve. It can be graphical explanation too.



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    You could consider using poly sources (vcvs) to create Vdd and the "switching input", a (say) 0-1V ramp at one terminal pair for the time varying aspect, a V=3.3 source multipled by the ramp is your rising Vdd and do the same scaling for a 0-Vdd pulse source through a second poly vcvs.

    Or you could go grab yourself a veriloga (or transistor level) inverter cell and string a couple together, powered off Vdd and passing the logic signal.



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    i just need to simulate a clock signal out of my Vdd which is a DC voltage(which could vary). I was simulating with a pulsed voltage source but i want to make it more realistic as it's not possible to have the clock amplitude differing from my vdd

    - - - Updated - - -

    Quote Originally Posted by dick_freebird View Post
    You could consider using poly sources (vcvs) to create Vdd and the "switching input", a (say) 0-1V ramp at one terminal pair for the time varying aspect, a V=3.3 source multipled by the ramp is your rising Vdd and do the same scaling for a 0-Vdd pulse source through a second poly vcvs.

    Or you could go grab yourself a veriloga (or transistor level) inverter cell and string a couple together, powered off Vdd and passing the logic signal.
    i'm trying to find something ideal because i don't want all the parasitic effects to be shown. I didn't get the poly source concept, could you explain it more?



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    Quote Originally Posted by iaf View Post
    does anyone have an idea which component in cadence lib would achieve that?
    Quote Originally Posted by iaf View Post
    i have in cadence a library called cadencelib which i'm using for simulating ideal components
    What do you want to mean by”Cadence lib” ?
    As far as I know, such library does not exist anywhere.
    Use correct terminology.

    Create custom signal source by Verilog-A.



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    Click image for larger version. 

Name:	cadence_lib.PNG 
Views:	6 
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ID:	153636
    That's the library i'm using



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    Quote Originally Posted by iaf View Post
    That's the library i'm using
    You can not understand tools which you use at all.

    They are just symbol’s library which are supplied with Cadence dfII.

    You can see available all Spectre primitives by “spectre -h”.
    Some of Spectre primitives are reflected as symbol in “analogLib” and “rfTlineLib”.

    You can see Verilog-A models in “ahdlLib”, “bmslib”, “rfLib”, “pllLib” and “pllMMLib”.
    However these are not useful for specific application.

    Create custom signal source by Verilog-A.
    Last edited by pancho_hideboo; 12th June 2019 at 11:09.



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    Quote Originally Posted by pancho_hideboo View Post
    You can not understand tools which you use at all.

    They are just symbol’s library which are supplied with Cadence dfII.

    You can see available all Spectre primitives by “spectre -h”.
    Some of Spectre primitives are reflected as symbol in “analogLib” and “rfTlineLib”.

    You can see Verilog-A models in “ahdlLib”, “bmslib”, “rfLib”, “pllLib” and “pllMMLib”.
    However these are not useful for specific application.

    Create custom signal source by Verilog-A.
    I'm not familiar with these expressions and don't know how to create something by verilog -A. Isn't there any ready component that could do this simple functionality?



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    The author is so unclear...
    What I have understood, the point here is to have square wave with 50MHz frequency, and levels between ground and vdd, while vdd is defined by another vdc source. This vdd is a variable. If so, use the same variable in vpulse component as second voltage.
    If my understanding is incorrect, please explain your issue clearly.

    BTW. VerilogA module or any more complicated stuff is not needed IMO



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    Ideal switch and behavioral voltage source have been previously suggested as possible solution. I'm sure they are somehow available in your schematic libraries. I don't use the tool, thus I can't help in this regard.



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    Quote Originally Posted by Dominik Przyborowski View Post
    The author is so unclear...
    What I have understood, the point here is to have square wave with 50MHz frequency, and levels between ground and vdd, while vdd is defined by another vdc source. This vdd is a variable. If so, use the same variable in vpulse component as second voltage.
    If my understanding is incorrect, please explain your issue clearly.

    BTW. VerilogA module or any more complicated stuff is not needed IMO
    that couldn't be achieved as setting the amplitude in a pulsed source couldn't be changed in a transient simulation, the same applies for the ideal switch it can't be switched in transient response



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    the same applies for the ideal switch it can't be switched in transient response
    No. Ideal switch means SPICE SW component is controlled by a pulsed voltage source, it's only use is in transient simulation.

    Similarly you can use behavioral voltage source, e.g. output voltage = product of voltage a and voltage b



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    Quote Originally Posted by FvM View Post
    No. Ideal switch means SPICE SW component is controlled by a pulsed voltage source, it's only use is in transient simulation.

    Similarly you can use behavioral voltage source, e.g. output voltage = product of voltage a and voltage b
    ok i have found this switch, i guess the vn and vp are the 2 nodes of the switch. are the vctrln/p the voltage sources i have to feed to control the switching of it? like how should i connect these 2 other nodes?



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    Re: Adding a pulsed switch to a dc voltage source in cadence library

    I have simulated the switch with the following parameters but it's still giving the input signal

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