ADF4351 RF setting Eval SW and ADIsimPLL

Question

Hi all, 
 This is a question about the ADF4350/ADF4351 Evaluation Board Software. 
 Q1 Grayed-out items that are automatically calculated in the RF settings section: After entering the RF frequency, channel spacing, and REF frequency, what formula is used to calculate N DIVIDER (INT, FRAC, MOD, Div) inside the software? I assume that ADIsimPLL also performs a similar calculation. Would you be able to disclose the formula/method of calculation? 
 Q2 I cannot reproduce the following ADF4351 EVAL GUI settings with ADIsimPLL. Is there a bug in the ADF4351 EVAL GUI or ADIsimPLL? I don't understand the relationship between the ADF4351 EVAL GUI and ADIsimPLL parameters. 
 The frequency settings are as shown in the EVAL GUI: RF Freq 470MHz REF Freq 25MHz PFD Freq 25MHz CH Spacing 100KHz Can you give me some advice?

Best regards, 
 sss

kieranb · Accepted Answer

Hi, 
 Attached is a text file containing the functions used to calculate the various parameters.

Fullscreen 
 ADF4351_IntFracCalc.txt 
 Download 
 
 #region Calculate N, INT, FRAC, MOD

 RFout = Convert.ToDouble(RFOutFreqBox.Text);
 REFin = Convert.ToDouble(RefFreqBox.Text);
 OutputChannelSpacing = Convert.ToDouble(OutputChannelSpacingBox.Text);

 PFDFreqBox.Text = (REFin * (RefDoublerBox.Checked ? 2 : 1) / (RefD2Box.Checked ? 2 : 1) / (double)RcounterBox.Value).ToString();
 PFDFreq = Convert.ToDecimal(PFDFreqBox.Text);


 




 #region Select divider
 if (RFout >= 2200)
 OutputDividerBox.Text = "1";
 if (RFout < 2200)
 OutputDividerBox.Text = "2";
 if (RFout < 1100)
 OutputDividerBox.Text = "4";
 if (RFout < 550)
 OutputDividerBox.Text = "8";
 if (RFout < 275)
 OutputDividerBox.Text = "16";
 if (RFout < 137.5)
 OutputDividerBox.Text = "32";
 if (RFout < 68.75)
 OutputDividerBox.Text = "64";
 #endregion


 if (FeedbackSelectBox.SelectedIndex == 1)
 N = ((decimal)RFout * Convert.ToInt16(OutputDividerBox.Text)) / PFDFreq;
 else
 N = ((decimal)RFout / PFDFreq);

 INT = (uint)N;
 MOD = (uint)(Math.Round(1000 * (PFDFreq / (decimal)OutputChannelSpacing)));
 FRAC = (uint)(Math.Round(((double)N - INT) * MOD));

 if (EnableGCD.Checked)
 {
 uint gcd = GCD((uint)MOD, (uint)FRAC);

 MOD = MOD / gcd;
 FRAC = FRAC / gcd;
 }

 if (MOD == 1)
 MOD = 2;

 INTBox.Text = INT.ToString();
 MODBox.Text = MOD.ToString();
 FRACBox.Text = FRAC.ToString();
 PFDBox.Text = PFDFreq.ToString();
 DivBox.Text = OutputDividerBox.Text;
 RFoutBox.Text = (((INT + (FRAC / MOD)) * (double)PFDFreq / Convert.ToInt16(DivBox.Text)) * ((FeedbackSelectBox.SelectedIndex == 1) ? 1 : Convert.ToInt16(DivBox.Text))).ToString();
 NvalueLabel.Text = (INT + (FRAC / MOD)).ToString();

I will send the simPLL file separately as it does not appear to upload.)

Electronic Design Services - PartnerZone

Products Mentioned

ADF4351 RF setting Eval SW and ADIsimPLL