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S-parameters from a RF Circuit - Circulator created from LC resonators

EduardoGS

Hello everyone.

I am trying to simulate, for my undergraduate thesis, a new RF circulator that was published by Nature Physics on article called "Magnetic-free non-reciprocity and isolation based on parametrically modulated coupled-resonator loops".

My doubt is how to create a setup that understands one RF signal (sweep from 140MHz to 200Mhz) modulated by a signal with fixed frequency (15Mhz) and that has phase 120º  difference between each one. After this, my goal is to plot S parameters and see the transmission from  port 1 to ports 2 and 3. My curent setup use QPSS and QPSP, but the results are not good.

I have the article and I can send to you to read and understand better the problem if you wish.

Best regards.

Parents

  • Hi,

    I did the simulation QPSS and QPSP replacing the varactor for a capacitor. On article have an information that says when VDC = 3V, the varactor has a capacitance 30pF. Then the results were better, but its still not correct. I think it the varactor model is wrong, but the manufacturer offers only that spice model.

    • Input.scs:

    // Generated for: spectre
    // Generated on: Sep 27 09:57:10 2016
    // Design library name: TCC2
    // Design cell name: circulador_2_TB
    // Design view name: schematic
    simulator lang=spectre
    global 0
    parameters C1=300p C2=30p Cc=5.6p Cdcb=10u Fm=15M Frf=170M L1=270n L2=27n \
    Lc=1u Lrfc=2.7u phi=120 Vdc=3.00 Vm=0.6
    include "/usr/local/IC614/tsmc13/tsmc13rf/../models/tsmc13rf.scs"

    // Library name: TCC2
    // Cell name: circulador_2
    // View name: schematic
    subckt circulador_2 Porta1 Porta2 Porta3 Porta4 Porta5 Porta6
    L14 (net30 Porta6) inductor l=Lrfc
    L13 (net33 0) inductor l=L1
    L12 (net27 Porta3) inductor l=Lc
    L11 (net27 net32) inductor l=L2
    L10 (net36 net27) inductor l=L2
    L9 (net24 Porta5) inductor l=Lrfc
    L8 (net34 0) inductor l=L1
    L7 (net21 Porta2) inductor l=Lc
    L6 (net21 net35) inductor l=L2
    L5 (net38 net21) inductor l=L2
    L4 (net18 Porta4) inductor l=Lrfc
    L3 (net15 Porta1) inductor l=Lc
    L2 (net31 net15) inductor l=L2
    L1 (net15 net39) inductor l=L2
    L0 (net37 0) inductor l=L1
    C11 (net30 net31) capacitor c=C1
    C12 (net18 0) capacitor c=C2
    C10 (net30 net33) capacitor c=Cdcb
    C9 (net32 net30) capacitor c=C1
    C8 (net27 Porta3) capacitor c=Cc
    C7 (net24 net36) capacitor c=C1
    C13 (net24 0) capacitor c=C2
    C6 (net24 net34) capacitor c=Cdcb
    C5 (net35 net24) capacitor c=C1
    C4 (net21 Porta2) capacitor c=Cc
    C14 (net30 0) capacitor c=C2
    C3 (net15 Porta1) capacitor c=Cc
    C2 (net18 net37) capacitor c=Cdcb
    C1 (net18 net38) capacitor c=C1
    C0 (net39 net18) capacitor c=C1
    ends circulador_2
    // End of subcircuit definition.

    // Library name: TCC2
    // Cell name: circulador_2_TB
    // View name: schematic
    I0 (net2 net3 net4 net1 net1 net1) circulador_2
    V0 (net1 0) vsource dc=Vdc type=dc
    PORT1 (net3 0) port r=50 type=sine freq=Fm ampl=Vm sinephase=1*phi \
    freq2=Frf dbm2=0 sinephase2=0 fundname="Modulation" fundname2="RF"
    PORT2 (net4 0) port r=50 type=sine freq=Fm ampl=Vm sinephase=-1*phi \
    freq2=Frf dbm2=0 sinephase2=0 fundname="Modulation" fundname2="RF"
    PORT0 (net2 0) port r=50 type=sine freq=Fm ampl=Vm sinephase=0*phi \
    freq2=Frf dbm2=0 sinephase2=0 fundname="Modulation" fundname2="RF"
    simulatorOptions options reltol=1e-3 vabstol=1e-6 iabstol=1e-12 temp=27 \
    tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 \
    digits=5 cols=80 pivrel=1e-3 sensfile="../psf/sens.output" \
    checklimitdest=psf
    qpss qpss flexbalance=yes oversample=[1 1] funds=["Modulation"
    + "RF"] maxharms=[3 3] errpreset=conservative annotate=status
    qpsp qpsp start=140M stop=300M portharmsvec=[0 0 0 0 0 0]
    + ports=[PORT0 PORT1 PORT2] annotate=status
    modelParameter info what=models where=rawfile
    element info what=inst where=rawfile
    outputParameter info what=output where=rawfile
    designParamVals info what=parameters where=rawfile
    primitives info what=primitives where=rawfile
    subckts info what=subckts where=rawfile
    saveOptions options save=allpub]

     

    • Results:

    At one frequency range, the S11 is lower than S21 and S31, but the device is behaving like a power divider (S21 = S31) and not like a circulator.

    Regards,

    Eduardo.

Reply

  • Hi,

    I did the simulation QPSS and QPSP replacing the varactor for a capacitor. On article have an information that says when VDC = 3V, the varactor has a capacitance 30pF. Then the results were better, but its still not correct. I think it the varactor model is wrong, but the manufacturer offers only that spice model.

    • Input.scs:

    // Generated for: spectre
    // Generated on: Sep 27 09:57:10 2016
    // Design library name: TCC2
    // Design cell name: circulador_2_TB
    // Design view name: schematic
    simulator lang=spectre
    global 0
    parameters C1=300p C2=30p Cc=5.6p Cdcb=10u Fm=15M Frf=170M L1=270n L2=27n \
    Lc=1u Lrfc=2.7u phi=120 Vdc=3.00 Vm=0.6
    include "/usr/local/IC614/tsmc13/tsmc13rf/../models/tsmc13rf.scs"

    // Library name: TCC2
    // Cell name: circulador_2
    // View name: schematic
    subckt circulador_2 Porta1 Porta2 Porta3 Porta4 Porta5 Porta6
    L14 (net30 Porta6) inductor l=Lrfc
    L13 (net33 0) inductor l=L1
    L12 (net27 Porta3) inductor l=Lc
    L11 (net27 net32) inductor l=L2
    L10 (net36 net27) inductor l=L2
    L9 (net24 Porta5) inductor l=Lrfc
    L8 (net34 0) inductor l=L1
    L7 (net21 Porta2) inductor l=Lc
    L6 (net21 net35) inductor l=L2
    L5 (net38 net21) inductor l=L2
    L4 (net18 Porta4) inductor l=Lrfc
    L3 (net15 Porta1) inductor l=Lc
    L2 (net31 net15) inductor l=L2
    L1 (net15 net39) inductor l=L2
    L0 (net37 0) inductor l=L1
    C11 (net30 net31) capacitor c=C1
    C12 (net18 0) capacitor c=C2
    C10 (net30 net33) capacitor c=Cdcb
    C9 (net32 net30) capacitor c=C1
    C8 (net27 Porta3) capacitor c=Cc
    C7 (net24 net36) capacitor c=C1
    C13 (net24 0) capacitor c=C2
    C6 (net24 net34) capacitor c=Cdcb
    C5 (net35 net24) capacitor c=C1
    C4 (net21 Porta2) capacitor c=Cc
    C14 (net30 0) capacitor c=C2
    C3 (net15 Porta1) capacitor c=Cc
    C2 (net18 net37) capacitor c=Cdcb
    C1 (net18 net38) capacitor c=C1
    C0 (net39 net18) capacitor c=C1
    ends circulador_2
    // End of subcircuit definition.

    // Library name: TCC2
    // Cell name: circulador_2_TB
    // View name: schematic
    I0 (net2 net3 net4 net1 net1 net1) circulador_2
    V0 (net1 0) vsource dc=Vdc type=dc
    PORT1 (net3 0) port r=50 type=sine freq=Fm ampl=Vm sinephase=1*phi \
    freq2=Frf dbm2=0 sinephase2=0 fundname="Modulation" fundname2="RF"
    PORT2 (net4 0) port r=50 type=sine freq=Fm ampl=Vm sinephase=-1*phi \
    freq2=Frf dbm2=0 sinephase2=0 fundname="Modulation" fundname2="RF"
    PORT0 (net2 0) port r=50 type=sine freq=Fm ampl=Vm sinephase=0*phi \
    freq2=Frf dbm2=0 sinephase2=0 fundname="Modulation" fundname2="RF"
    simulatorOptions options reltol=1e-3 vabstol=1e-6 iabstol=1e-12 temp=27 \
    tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 \
    digits=5 cols=80 pivrel=1e-3 sensfile="../psf/sens.output" \
    checklimitdest=psf
    qpss qpss flexbalance=yes oversample=[1 1] funds=["Modulation"
    + "RF"] maxharms=[3 3] errpreset=conservative annotate=status
    qpsp qpsp start=140M stop=300M portharmsvec=[0 0 0 0 0 0]
    + ports=[PORT0 PORT1 PORT2] annotate=status
    modelParameter info what=models where=rawfile
    element info what=inst where=rawfile
    outputParameter info what=output where=rawfile
    designParamVals info what=parameters where=rawfile
    primitives info what=primitives where=rawfile
    subckts info what=subckts where=rawfile
    saveOptions options save=allpub]

     

    • Results:

    At one frequency range, the S11 is lower than S21 and S31, but the device is behaving like a power divider (S21 = S31) and not like a circulator.

    Regards,

    Eduardo.

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