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Create ideal buffer with verilogA

BaaB

Hi,

With the help of Andrew last time relating to dependent sources, yesterday I tried a similar approach to create an ideal buffer.

I tried it and tested. Everything is OK. However, I have some questions relating to the code. Could you help me clarify it?

Here is the code I used to create an ideal buffer:

subckt ibuff (in out gnd)
V1 (out gnd) bsource v=v(in,gnd)
ends ibuff


It works as expected. But how input impedance of infinity and zero output impedance is realized from the code?

I see that the ideal buffer has infinite input impedance and zero output impedance too

Parents

  • Thanks for the help. I was not sure how the input voltage is measured in simulator. But from what you said, it draws no current when measuring so it has infinite input impedance then.

    I also thought about vcvs but I haven't tried that.

    For the code, could you tell me how to include that code to make it work?

    I tried the way as you said last time for dependent source but I got the following errors:

    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libinfineon_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libphilips_o_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libphilips_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libsparam_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libstmodels_sh.so ...
    Reading file:  /home/huannguyen/simulation/ibuff_tb/spectre/schematic/netlist/input.scs
    Reading file:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/configs/spectre.cfg
    Reading file:  /home/huannguyen/TSMC65/models/spectre/crn65gplus_2d5_lk_v1d0.scs
    Reading file:  /home/huannguyen/TSMC65/models/spectre/mosCAPrf_ahdl.va
    Reading link:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/constants.h
    Reading file:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/constants.vams
    Reading link:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/discipline.h
    Reading file:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/disciplines.vams
    Reading file:  /home/huannguyen/TSMC65/models/spectre/mosCap_ahdl.va
    Reading file:  /home/huannguyen/ibuff.scs

    Error found by spectre during circuit read-in.
        ERROR (SFE-841): "/home/huannguyen/ibuff.scs" 1: Unexpected character ``' in netlist.
        ERROR (SFE-868): "/home/huannguyen/ibuff.scs" 1: Can not open input file `disciplines.vams'. No such file or directory. Ensure that the file exists and the path to the file is correct. Otherwise, use the -I<path> command-line option to specify the path to the file.
    Warning from spectre during circuit read-in.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 2: Use of the comma character in node lists is not supported.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 2: Use of the comma character in node lists is not supported.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 3: Use of the comma character in node lists is not supported.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 3: Use of the comma character in node lists is not supported.
    Error found by spectre during circuit read-in.
        ERROR (SFE-678): "/home/huannguyen/ibuff.scs" 8: Statement is not in Spectre format. Use `simulator lang=spice' to introduce spice language sections.
        ERROR (SFE-678): "/home/huannguyen/ibuff.scs" 11: Statement is not in Spectre format. Use `simulator lang=spice' to introduce spice language sections.

Reply

  • Thanks for the help. I was not sure how the input voltage is measured in simulator. But from what you said, it draws no current when measuring so it has infinite input impedance then.

    I also thought about vcvs but I haven't tried that.

    For the code, could you tell me how to include that code to make it work?

    I tried the way as you said last time for dependent source but I got the following errors:

    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libinfineon_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libphilips_o_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libphilips_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libsparam_sh.so ...
    Loading /usr/cadence/MMSIM151/tools.lnx86/cmi/lib/64bit/5.0/libstmodels_sh.so ...
    Reading file:  /home/huannguyen/simulation/ibuff_tb/spectre/schematic/netlist/input.scs
    Reading file:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/configs/spectre.cfg
    Reading file:  /home/huannguyen/TSMC65/models/spectre/crn65gplus_2d5_lk_v1d0.scs
    Reading file:  /home/huannguyen/TSMC65/models/spectre/mosCAPrf_ahdl.va
    Reading link:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/constants.h
    Reading file:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/constants.vams
    Reading link:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/discipline.h
    Reading file:  /usr/cadence/MMSIM151/tools.lnx86/spectre/etc/ahdl/disciplines.vams
    Reading file:  /home/huannguyen/TSMC65/models/spectre/mosCap_ahdl.va
    Reading file:  /home/huannguyen/ibuff.scs

    Error found by spectre during circuit read-in.
        ERROR (SFE-841): "/home/huannguyen/ibuff.scs" 1: Unexpected character ``' in netlist.
        ERROR (SFE-868): "/home/huannguyen/ibuff.scs" 1: Can not open input file `disciplines.vams'. No such file or directory. Ensure that the file exists and the path to the file is correct. Otherwise, use the -I<path> command-line option to specify the path to the file.
    Warning from spectre during circuit read-in.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 2: Use of the comma character in node lists is not supported.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 2: Use of the comma character in node lists is not supported.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 3: Use of the comma character in node lists is not supported.
        WARNING (SFE-702): "/home/huannguyen/ibuff.scs" 3: Use of the comma character in node lists is not supported.
    Error found by spectre during circuit read-in.
        ERROR (SFE-678): "/home/huannguyen/ibuff.scs" 8: Statement is not in Spectre format. Use `simulator lang=spice' to introduce spice language sections.
        ERROR (SFE-678): "/home/huannguyen/ibuff.scs" 11: Statement is not in Spectre format. Use `simulator lang=spice' to introduce spice language sections.

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