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Simulators >> Circuit Simulators >> using spectre to build the pll behavioral model
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Message started by calven on Apr 7^th, 2007, 9:01am

Title: using spectre to build the pll behavioral model
Post by calven on Apr 7^th, 2007, 9:01am

hi!
should i build the models of basic cells such as vco using verilog_a or verilogams if i use spectre to build the pll mode?i find that these cells are offered in the libs such as functional,ahdl and rfLib bu virtuso, can these cells not fully describe the characters of real cells?
thanks a lot!

Title: Re: using spectre to build the pll behavioral mode
Post by sheldon on Apr 7^th, 2007, 8:18pm

Calven,

If you are going to build a PLL model for Spectre, then the models need to written
in Verilog-A. AMS Designer supports Verilog-AMS. There are some model templates,
on this site under the Verilog-AMS link

http://www.designers-guide.org/VerilogAMS/

There is a lot of information about PLL modeling under the Analysis link including

http://www.designers-guide.org/Analysis/PLLnoise+jitter.pdf

Ken's classic paper of behavioral modeling of PLLs. One other library that may be useful
in the Cadence libraries is bmslib it contains Verilog-A primitives for logic gates that can
be used to create Phase/Frequency Detectors.

Best Regards,

Sheldon

Title: Re: using spectre to build the pll behavioral mode
Post by calven on Apr 8^th, 2007, 9:21pm

thanks a lot!
what is the difference between Verilog-A and VerilogAMS?which one should i choose?

Title: Re: using spectre to build the pll behavioral mode
Post by Geoffrey_Coram on Apr 9^th, 2007, 3:52am

Verilog-A is the "analog only" subset of Verilog-AMS, which is a full analog and mixed-signal language and includes (in principle) everything from IEEE 1364 Verilog.