Hi Andrew,

Not an expert, buy my intuition says use the SE4150L part.  My questions
then are,

*  will this part meet anticipated needs longer term or long enough?
*  will our work to use this part be transferable to a next generation
design?

My thought it that it is better to have higher bandwidth for this
application, even if there is some work to do to keep power use and
complexity down in circuits designed to meet that higher bandwidth.

The part with little or no datasheet sounds like a dicey proposition to use.

- Ted

On Fri, Feb 6, 2015 at 3:15 AM, Andrew Greenberg <a...@ece.pdx.edu> wrote:

> While laying out the third version of the jGPS board, it suddenly
> occurred to me: we chose the MAX2769 because we were goaded into
> thinking that the serial output was actually... well, serial. And not
> some weird strange bizarre useless thing, as it really is. Since it's
> not usefully serial, we're switching the MAX2769 to parallel mode,
> throwing the output at a CPLD, and then putting SPI'ing it into the
> STMF407.
>
> So: if we're doing the MAX in parallel mode, why not look at *other* RF
> front end ICs, and use them? I found two:
>
> The ST STA5630. This one looks great, but is useless because there's no
> useful datasheets on this chip. So, no.
>
> The Skyworks SE4150L [1] is just the old SiGe SE4150L made now by
> Skyworks. It's a dumb and easy chip to use: no SPI, no configuration to
> speak of, and it only outputs 2 bit Mag/Sign data. So we lose a couple
> of bits, but we now have no weird configuration problems. But it has a
> serious problem for us: the IF is 4.092 MHz, and the sample rate is
> 16.384 MHz. So that's 32.768 Mbps, which is a whole lot of data, and is
> > 25 Mbps of the usual SPI limits. On the other hand, at those rates we
> get real bandwidth.
>
> Currently on the MAX2769 [2], our IF is 2.048 MHz, the sample rate is
> 4.096 MHz at 4 bits, so our bitrate is 16.384 Mbps.
>
> In a nutshell:
>
> - SE4150L = less bits, more data, more bandwidth, simple
> - MAX2769 = more bits, less data, less bandwidth, complicated
>
> Anyone have anything to say about this? I'd appreciate thoughts on this!
>
> Thanks!
>
> Andrew
>
> [1] http://www.skyworksinc.com/Products.aspx?CategoryID=562
> [2]
> http://www.maximintegrated.com/en/products/comms/wireless-rf/MAX2769.html
>
> --
> -------------------------------------------------------
> Andrew Greenberg
>
> Electrical and Computer Engineering
> Portland State University
> http://www.ece.pdx.edu/
> a...@ece.pdx.edu  C: 503.708.7711
> -------------------------------------------------------
>
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