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 cheap_salary Senior Member Offline Posts: 162 Nonlinear operation of small signal noise in Verilog-A Oct 15th, 2015, 8:33am   See LISTING-8 at page-22 in the following. http://www.designers-guide.org/Analysis/PLLnoise.pdfPhase-domain fractional-N divider is modeled like following. Code:```Theta(out) <+ Theta(in) / ( ratio + noise_table(...) ); ```I can easily understand this expression if it is for Transient Noise Analysis.However this expression is for small signal noise analysis.How is this expression treated in small signal noise analysis ?I think this is Nonlinear operation of small signal noise.Synopsys HSPICE and Cadence Spectre gives fairly different noise result.Can it be valid such Nonlinear operation for small signal noise analysis ? Back to top IP Logged
 cheap_salary Senior Member Offline Posts: 162 Re: Nonlinear operation of small signal noise in Verilog-A Reply #5 - Oct 24th, 2015, 2:31am   Since the following is defined in this module. Code:```parameter real fc = 0 from [0:inf); // flicker noise corner frequency (Hz) ```I think noise implementation should be like following.   Quote:Theta(out) <+ Theta(in) / ratio;Theta(out) <+ flicker_noise(n*fc, 1, "fpn");Theta(out) <+ noise_table({                            0, n,                           bw, n,                         fmax, n*pow((fmax/bw), 2*order)                           }, "dsn")); or Quote:Theta(out) <+ Theta(in) / ratio;Theta(out) <+ flicker_noise(n*fc, 1, "fpn");Theta(out) <+ white_noise(n, "wpn")Theta(out) <+ noise_table({                           bw, 0,                         fmax, n*pow((fmax/bw), 2*order)                           }, "dsn")); Back to top IP Logged