"For optimum performance, the 4LOx inputs are driven differentially but can also be driven single ended. A good choice for a drive is an LVDS device." (Like the SDR-1000 uses on the outputs of the DDS) ... I'm sure the inputs can be single ended also with the other input tied to ground through a cap ... I think I'd intially experiment with single ended inputs and then when I got a well working circuit, improve it with differential inputs and clock
My main concern with this IC is in order to get an even decent NF you have to use an RF preamp ... this tells me (and it isn't noted anywhere) that the NF without a preamp is not very good .... the problem with using a preamp is you IP3 goes down by the amount of gain in the preamp (This is a compromise necessary in all receiver design, NF and third order intercept oppose each other and you have to decide which is most important and how much you are willing to sacrifice from one to gain in the other) and the only NF specs are WITH the suggested preamp and the IP3 specs are without the preamp (I hate it when Marketing and not Engineering runs the Specmanship Game) I'm not saying it's necessarily a bad part but a Tayloe/QSD ala the SDR-1000, NC2030 or the Softrock is going to perform a lot better both in NF and IP3 ... it's main plus is convenience of use and in many applications it will good enough, it's just not going to have the exceptional dynamic range of a Tayloe based receiver .... it would also be great in a dual diversity antenna system which looks to be a wide open field for SDR experimenters JR --- In [email protected], "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > > > Looking ahead here at what we are getting into. With enough samples > to recover from a mistake, this is something I noted. If someone > better knows whats up in this chip than I have figured here, then help > us with that insight. > > Looking at the inputs to the AD8333 Evaluation Board Circuit Diagram > it shows that they each have a + / - input as if they are all balanced > inputs? If this is so, I am seeing then that the input from the > antenna to CH1 and CH2 will need to come from a toroid with two in > phase secondary windings. > > The LO IN is depicted also as having what looks like a balanced > input. And likewise may need to be fed with a toroid secondary. This > I suppose then is the first thing to check on the breakout boards. > > The inputs all seem to be depicted in the evaluation board schematic > as having "DC isolation capacitors" on each side of the presently > "assumed" balanced inputs. So the toroid secondaries can not be such > that they allow direct current to pass from the + to -. > > In figure 13 of the Analog Devices AD8333 PDF, the capacitors are > depicted as CH1 = C22, C23, LO IN = C15, C16, CH2 = C19, C20. > > These inputs also look allot like Linear Integrated IC inputs? I > don't think this is what this is. So I am thinking that these are > hence balanced inputs with DC blocking isolation across them. > > The I/Q outputs also have two lines going out and this seems for > Linear Integrated IC amplifiers in this case. So I guess when we get > that far we will see what we have to do then. I need to go and look up > the various IC types and become re~acquainted with which are what here. > > With Gilbert Cells I can easily imagine this being so, having > balanced inputs and outputs. And we will then need two toroids for > this IC. > > I have the ARRL HB on CD Rom here and can look up the Gilbert Cell > and post that here. > > > > > _____________________________________________________________________ > PrivatePhone - FREE telephone number & voicemail. > A number so private, you can make it public. > http://www.privatephone.com > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/soft_radio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
