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  3. Query regarding the Verilog-A code given under "Modeling...

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Query regarding the Verilog-A code given under "Modeling Oscillators with Arbitrary Phase Noise Profiles"

RFStuff
RFStuff over 8 years ago

Dear All,

I was trying to understand the Verilog-A code given under "Modeling Oscillators with Arbitrary Phase Noise Profiles" .

( see the link  http://support.cadence.com/wps/myportal/cos/COSHome/viewsolution/!ut/p/a1/nY_LDoIwEEW_hQ8wnUKhsKyPgKWBqBhpNwYiMY28guDCrxeMiSs1cXYzOXNmLlIoRarObvqc9bqps3LqlXNc4xXBQQzc99gCGNAN34fYDKk9AnIE4EMx-LV_QOqJfDHI8QR9O1whPGB-6GwDmlgQU7Svm64an91NrlNRtELXFyT7biimybUphylONFR50SGJMaW24zovsR0sCXDAPJ6bFFiQEJ9EAkNs_i1uqxRmsnItW-d3ZhgPAm41FA!!/dl5/d5/L2dBISEvZ0FBIS9nQSEh/ )

 


I want to know the meaning of the two lines present in that verilog-A code:-  ( What they are meant for ?)

isource #(.type("sine"), .ampl(`pow2v(`dbm2pow(power),rout)/rout), .freq(freq) ) is1(gnd,out);

vsource #(.type("sine"), .ampl(`pow2v(`dbm2pow(power),rout)/rout), .sinephase(-90), .freq(freq) ) vs1(gnd,int);

 

 


The code is as below:-

`define db10_real(x) pow(10, (x)/10)

`define dbm2pow(x) `db10_real( ((x)-30) )

`define pow2v(x,r) sqrt(8*(r)*(x))

module oscwphnoise(out, ph);

inout out;

input ph;

electrical out;

electrical ph;

electrical gnd;

ground gnd;

electrical int;

parameter real power = 10 ;

parameter real rout = 50 ;

parameter real freq = 1e+09 ;

isource #(.type("sine"), .ampl(`pow2v(`dbm2pow(power),rout)/rout), .freq(freq) ) is1(gnd,out);

vsource #(.type("sine"), .ampl(`pow2v(`dbm2pow(power),rout)/rout), .sinephase(-90), .freq(freq) ) vs1(gnd,int);

analog begin

I(out) <+ -V(int)*V(ph);

I(out) <+ V(out)/rout;

end

endmodule
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  • Tawna
    Tawna over 8 years ago
    Hi RFStuff,
    It's best to submit questions by clicking on the Feedback link in support.cadence.com . That way, the article can be enhanced. This was a methodology developed prior to MMSIM13.1 (and has been kept for legacy purposes...I've been debating removing the article from Cadence Online Support).

    From MMSIM13.1 and later releases, we recommend that you use the methodology in Article 20256770  How to specify phase noise as an instance parameter in spectre sources (e.g. vsource, isource, port) support.cadence.com/.../cos;solutionNumber=20256770 . It is much easier.

    best regards,
    Tawna
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  • RFStuff
    RFStuff over 8 years ago

    Hi Tawna,

    Thanks for your reply.

    We observed that  using the method (e.g. vsource, isource, port) support.cadence.com/.../cos;solutionNumber=20256770 ), the Phase noise profile is NOT coming as desired for the following SSB noise vs Frequency input.

    10    -69 dBc

    100  -89 dBc

    1000  -102 dBc

    10000  -112 dBc

    100000 -140dBc

    Could you please tell why this phase noise profile is NOT working ?

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  • RFStuff
    RFStuff over 8 years ago
    To add to the above query:- Is it some folding is happening ( Unless the PORT method automatically makes the noise profile to very very low value beyond half-Oscilation frequency)
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  • Tawna
    Tawna over 8 years ago
    Hi RF Stuff,
    Would you please file a Case with Cadence Online Support? http://support.cadence.com . (you can put me on the cc list for the Case you file).

    Andrew and I typically answer questions "on our own time" (which is in extremely short supply right now). This is going to take a bit of investigation and to work on this, I'll need a Case. Thanks in advance!

    best regards,
    Tawna
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  • RFStuff
    RFStuff over 8 years ago

    Hi Tawna,

    I have filed a request for this case. 

    But, as per the rule and regulation of the forum , I should NOT have posted the same issue here. 

    However, since you advised this methodology to follow, I have posted the issue with this method. ( thinking that you might be knowing the root cause)

    But, again strictly speaking, I should NOT have posted the same case.

    Having said this, I have requested the AE to keep you in the cc.

    Kind Regards,

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