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Design Languages >> Verilog-AMS >> Phase Unwrap
https://designers-guide.org/forum/YaBB.pl?num=1476464850

Message started by WishToRemainAnonymous on Oct 14^th, 2016, 10:07am

Title: Phase Unwrap
Post by WishToRemainAnonymous on Oct 14^th, 2016, 10:07am

Hello All. I have a Veriloga code for phase unwrap block used in phase to voltage converter block that has been suggested in

http://delivery.acm.org/10.1145/1330000/1326256/p887-kim.pdf?ip=17.236.17.12&id=1326256&acc=ACTIVE%20SERVICE&key=C8755068B4FD57B4%2EC8755068B4FD57B4%2E4D4702B0C3E38B35%2E4D4702B0C3E38B35&CFID=852135067&CFTOKEN=88951952&__acm__=1476464484_698bd9f31c19dcf2e125c82cf3f3163f

The code is given below.

Code:

`include "constants.vams"
`include "disciplines.vams"

module phase_unwrap(c,s,out);

input c,s;
output out;

voltage c,s,out;

parameter k=1e7;

real te,co,so;

analog begin

@(initial_step)
begin
te=0;
co=1;
so=0;
end

co=cos(V(out));
so=sin(V(out));

te=atan2(V(s)*co-V(c)*so,V(s)*so+V(c)*co);

V(out) <+ `M_PI*2*k*idt(te,`M_PI/4);

end
endmodule

There is an IQ demodulator block whose I and Q components are fed to the "c" and "s" inputs of the phase unwrap block. The phase unwrap block has an integrator block in it and an atan2 function which extracts the angle from the c and s inputs. Details of this block are given in the paper whose link I have pointed to above.

This block has a convergence issue. Unless I use "sigramp" option, this never converges. There are times when this cell works fine without "sigramp" option but then the output blows up.

I need your advice to somehow make this block more friendly towards convergence. I would greatly appreciate your help with this problem of mine.

Title: Re: Phase Unwrap
Post by Ken Kundert on Oct 14^th, 2016, 11:38am

Your link is broken.

Title: Re: Phase Unwrap
Post by WishToRemainAnonymous on Oct 14^th, 2016, 11:43am

Sorry about that. Wonder why the url would not work.

I am pasting the url below.

http://delivery.acm.org/10.1145/1330000/1326256/p887-kim.pdf?ip=17.236.17.12&id=1326256&acc=ACTIVE%20SERVICE&key=C8755068B4FD57B4%2EC8755068B4FD57B4%2E4D4702B0C3E38B35%2E4D4702B0C3E38B35&CFID=852135067&CFTOKEN=88951952&__acm__=1476470776_a844bf1574c6a6ddab3bc8c62ffbec93

It is a paper on Variable Domain Transformations and the ACM website for that is

http://dl.acm.org/citation.cfm?id=1326256

You can click on the pdf link to download the pdf from there.