[hpsdr] ADC Question

[Phil Harman]

Hi Larry,

I confirm that the LTC2209 is a drop-in replacement for the 2208 and runs fine at a higher clock frequency since I have one installed on a Mercury board.

The NF of the LTC2208 is about 30 dB  (as long as you don’t follow the data sheet and resistively terminate the input) so is usable up to about 17 m without a preamp when connected to an efficient antenna. 

73 Phil....VK6APH 



From: Larry Gadallah 
Sent: Friday, July 27, 2012 11:36 AM
To: Andrew 
Cc: hpsdr at lists.openhpsdr.org 
Subject: Re: [hpsdr] ADC Question

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Hi Andrew:


On 26 July 2012 13:46, Andrew <irbsurfing at yahoo.co.uk> wrote:

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  Hi Larry,
  Unfortunately the LTC2207 and LTC2208 are not pin compatible, the former is 48 pin QFN and the latter a 64 pin due to the use of LVDS for the output data lines.

Hmmm, I must have confused it with the LTC2209. Regardless, the point is that it would be interesting to experiment with an HF-only arrangement where an ADC with the absolute best ENOB and SFDR was used in an attempt to get a bit closer to analog Rx performance without needing a preamp. >From my casual research it doesn't look like anyone (TI, LTC, ADC) has anything much more than 2-3 dB better than the LTC2208, so it seems that this might be a process/technology limitation.

  I had already thought about doing this! Trying to make it fit would be very interesting and not recommended without a specially designed pcb carrier - that just might work.....mmm.


I keep thinking that if we limit ourselves to a maximum Rx frequency of 30 MHz or so, it should be possible to build a nice little Rx with 100-Base-T Ethernet (maybe even PCI). It probably wouldn't be much cheaper than Mercury given the costs of the ADC and FPGA, but it would be getting close to having a "blade" receiver architecture :-).

  73's,
  Andrew

Cheers,
-- 
Larry Gadallah, VE6VQ/W7                          lgadallah AT gmail DOT com
PGP Sig: B5F9 C4A8 8517 82AC 16B6  02B6 0645 69F0 1F29 A512



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