[USRP-users] USRP N210 WBX Board | ADF 4350 VCO IC Not getting Configured

Rohit Kulkarni k.rohit.u at gmail.com
Wed Nov 15 20:27:39 EST 2017


I am working on USRP N210 with a WBX (Revision 2) daughterboard. The WBX
daughterboard uses ADF 4350 to generate a frequency signal which feeds into
the mixer in the RX chain.

We want to have a control over the frequency signal generated by ADF 4350
(this is a differential signal available on pins RFOut A+/-) and hence we
have erased the connection between CPout pin to Vtune pin and feed a
constant (or varying) voltage signal to Vtune pin. (This signal is
generated externally through say a voltage power supply). We then run
uhd_fft -f <some frequency> to set up the default register values within
ADF 4350 and try to feed a voltage signal of constant or varying magnitude
between 0.5V to 2.4V.

When we monitor the frequency signal coming out of RFOutA+/- we see that
it's a constant frequency signal which varies only when we run uhd_fft with
a different frequency setting. Frequency signal does not vary as we sweep
our voltage signal (feeding to Vtune) from 0.5V to 2.4V.

Assuming that all the connections are proper and we are feeding a valid
voltage signal to Vtune, can someone tell me what might be going wrong
possibly in our setup?

For your reference, this is the schematic of the WBX daughterboard (check
page 3) - https://files.ettus.com/schematics/wbx/WBX.pdf

Datasheet of ADF 4350 -

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