AnsweredAssumed Answered

HMC835LP6GE VCO AutoCal example in datasheet pg 25.

Question asked by MartyMcConnell on Apr 10, 2015
Latest reply on Apr 16, 2015 by DonY

I'm working through the equations for the provided AutoCal example and I don't get the same Tcal result as shown in Table 3.  Using all the same inputs and getting the same Tmmt and Ferr values for row 1, but the Tcal value is about 2x those in the table.  I've triple checked the equation.  Can anyone confirm this too?  Is the table incorrect?

 

Thanks.

 

           

Ref Freq.5.00E+07Txtal2.00E-08
Output Freq.2.01E+09FPD5.00E+07TPD2.00E-08
FVCO1.25E+09
Eq. 1AutoCal Time & AccuracyRegisterValueRegisterValue
Tmmt2.00E-080Ah[2:0]n002hR1
Eq. 2Ratio target VCO freq. to PD freq.
N2.50E+0103hNint2504hNfrac0
Eq. 3FSM Time
TFSM2.00E-080Ah[14:13] 0->m0
Eq. 4Expected # of VCO counts
V2.50E+01
Eq 5.VCO Frequency Measured
FVCOM1.25E+09
Eq 6.Frequency Error
Ferr2.50E+07
Eq 8.Calibration Time
Tcal1.06E-05

Outcomes