PLL LMX2326

[Hervé]

HI,

I plan to use a LMX2326 (NS) with a large bandwidth VCO (zcomm v674me02).
I don't want to use an active loop filter, but my VCO needs Vtuning from 1
to 14 V.

Can I use a passive loop filter when connecting VP (on lmx2326) connected to
+15V dc ?

Regards

Herve

 

[Rene Tschaggelar]

HI,

I plan to use a LMX2326 (NS) with a large bandwidth VCO (zcomm v674me02).
I don't want to use an active loop filter, but my VCO needs Vtuning from 1
to 14 V.

Can I use a passive loop filter when connecting VP (on lmx2326) connected to
+15V dc ?

A passive loop filter operates on the voltage or current coming out of
the phase detector. If the LMX2326 allows that, then it should work.

Rene

 

[Allan Herriman]

HI,

I plan to use a LMX2326 (NS) with a large bandwidth VCO (zcomm v674me02).
I don't want to use an active loop filter, but my VCO needs Vtuning from 1
to 14 V.

Can I use a passive loop filter when connecting VP (on lmx2326) connected to
+15V dc ?

The datasheet says VP abs. max voltage with respect to ground is 6.5V
(and recommended max is 5.5V).

Regards,
Allan.

 

[John Miles]

HI,

I plan to use a LMX2326 (NS) with a large bandwidth VCO (zcomm v674me02).
I don't want to use an active loop filter, but my VCO needs Vtuning from 1
to 14 V.

Can I use a passive loop filter when connecting VP (on lmx2326) connected to
+15V dc ?

Nope. The charge pump voltage pin only accepts up to 6 (maybe 7?)
volts. You'll need an outboard gain stage.

-- jm

 

[Richard Hosking]

The datasheet is at http://www.national.com/pf/LM/LMX2326.html#Datasheet

It looks like the max volts to Vp is +6.5V.
For a wideband VCO you might be better to use a separate opamp for best
phase noise
see http://www.qsl.net/ke5fx/synth.html for a wideband microwave PLL circuit
using this chip

Richard