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Passive switching mixer volatge conversion gain calculation and its varition with frequency

lahsivece

Hi All,

I am trying to do a passive switching mixer volatge conversion gain simulation. The circuit consists of a MOS transistor driving a resistive load. The gate of MOS is driven by a rail to rail square pulse. 

I tried the steps given in the Application note "Mixer design using Spectre RF " , but it didn't give meaningful results.

Is there any application note that deals specifically with passive switching mixers with LO being driven by a rai to rail signal or a similar situation ?

Best Regards

Vishal

Parents
  • Hi Andrew,

    Pictures were attached . Any way here is the whole post again

    Hi Andrew ,

    Sorry for not being clear. I am not getting a correct voltage gain from passive swictging mixer . The test bench looks like following :

     Please refer to image

    The input.scs file is :

    // View name: schematic
    PORT0 (RF 0) port r=50 dc=600m type=dc freq=frf dbm=vrf pacmag=1
    V1 (LO 0) vsource type=pulse val0=0 val1=1 period=tlo width=d*tlo
    M0 (IF LO RF 0) N_12_RF wf=5u lf=120.0n nf=4 m=1
    R0 (IF 0) capacitor c=c1
    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
    pss  pss  fund=500M  harms=100  errpreset=moderate  annotate=status
    pac  pac  start=1K  stop=500M  maxsideband=2  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
     

    c1=500f

    The simulated gain curve from pss+swept pac is

    Please refer to gain_curve.png image.

    I belive that this is wrong.

    I also calculated gain as VIF/VRF from PSS analysis  which at 10MHz IF comes to be -4.6dB. The input.scs looks like folowing :

    // Cell name: RX_MIXER_FUNDAMENTAL_RZ_MOS_SW
    // View name: schematic
    R0 (IF 0) capacitor c=c1
    M0 (IF LO RF 0) N_12_RF wf=5u lf=120.0n nf=4 m=1
    V1 (LO 0) vsource type=pulse val0=0 val1=1 period=tlo width=d*tlo
    V0 (RF 0) vsource dc=600.0m type=sine ampl=vrf freq=frf
    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
    dcOp dc write="spectre.dc" maxiters=150 maxsteps=10000 annotate=status
    dcOpInfo info what=oppoint where=rawfile
    pss  pss  fund=10M  harms=200  errpreset=conservative
    +    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

    Please advise as to what is going wrong with a pss+swept pac simulation.

     Thanks,

    With Best Regards

    Vishal
Reply
  • Hi Andrew,

    Pictures were attached . Any way here is the whole post again

    Hi Andrew ,

    Sorry for not being clear. I am not getting a correct voltage gain from passive swictging mixer . The test bench looks like following :

     Please refer to image

    The input.scs file is :

    // View name: schematic
    PORT0 (RF 0) port r=50 dc=600m type=dc freq=frf dbm=vrf pacmag=1
    V1 (LO 0) vsource type=pulse val0=0 val1=1 period=tlo width=d*tlo
    M0 (IF LO RF 0) N_12_RF wf=5u lf=120.0n nf=4 m=1
    R0 (IF 0) capacitor c=c1
    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
    pss  pss  fund=500M  harms=100  errpreset=moderate  annotate=status
    pac  pac  start=1K  stop=500M  maxsideband=2  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
     

    c1=500f

    The simulated gain curve from pss+swept pac is

    Please refer to gain_curve.png image.

    I belive that this is wrong.

    I also calculated gain as VIF/VRF from PSS analysis  which at 10MHz IF comes to be -4.6dB. The input.scs looks like folowing :

    // Cell name: RX_MIXER_FUNDAMENTAL_RZ_MOS_SW
    // View name: schematic
    R0 (IF 0) capacitor c=c1
    M0 (IF LO RF 0) N_12_RF wf=5u lf=120.0n nf=4 m=1
    V1 (LO 0) vsource type=pulse val0=0 val1=1 period=tlo width=d*tlo
    V0 (RF 0) vsource dc=600.0m type=sine ampl=vrf freq=frf
    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
    dcOp dc write="spectre.dc" maxiters=150 maxsteps=10000 annotate=status
    dcOpInfo info what=oppoint where=rawfile
    pss  pss  fund=10M  harms=200  errpreset=conservative
    +    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

    Please advise as to what is going wrong with a pss+swept pac simulation.

     Thanks,

    With Best Regards

    Vishal
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