On Jul 2, 8:05 am, wrote:
On Sun, 01 Jul 2007 11:48:15 -0700, wrote:
I was considering a Hittite HMC580ST89 InGaP HBT Gain Block
which has a NF of 2.8, covers DC - 1 GHz, and is easy to use
(i.e. can operate directly from +5V).

It's a nice package, I've used it. But, what are you putting before
that to prevent a Pager at 153mhz from completely overloading it?

A SAW filter.

Currently the design calls for using a AD9952 DDS followed by
a 10.7 MHz BW=300 kHz crystal filter to provide the reference
for a ADF4002 PLL controlling a UMC VCO. ADIsimPLL claims
phase noise of -107 at 10 kHz.

The LO sounds ok but the 300khz filter?? Thats FM broadcast
wide. The wider the IF the worse the system NF will be

The 300kHz filter is for the DDS output which is the reference for
the PLL so that I can vary the reference frequency enough to generate
a precise LO. It is not the filter for the IF.

-- John