LMX2491: LMX2491

Agxin Justin xavier

Part Number: LMX2491

Tool/software:

I am using LMX2491 With BGTMTR11

The o/p from MTR11 Used to compare is /16 of Fout , I am trying to understand the PLL-atinum Sim to fix the values of loop filter to work stable for the frequency range from 24 -24.2 ghz

But the loop filter after 24.1 o/p is oscillating so I am trying to retune the filter

so the inputs to the software the FOSC is 20MHZ

The charge pump output current is set to 3.1mA how do i set KVCO and VCO cap ?

KVCO

Current values in the design which creates oscillation

8 months ago

0 Noel Fung 8 months ago

TI__Guru** 111030 points

Hi There,

Usually we take the geometric mean, so the Kvco = sqrt (Kvco,min x Kvco,max) = 447.2MHz/V.

Since the Fin frequency is div/16, so does the Kvco.

There is no VCO input capacitance from the datasheet, we assume it is nil.

An example loop filter design:

0 Agxin Justin xavier 8 months ago in reply to Noel Fung

Intellectual 380 points

In one of the PLL after certain frequency range the O/P of Vtune is having the ripple and because of that the o/p is oscillating

Clock & timing

Clock & timing forum

LMX2491: LMX2491