Over the last two years along with two list members that may want to pipe in, I have spend a large amount of time on D/A's and we went as far as developing a test board using the LTC 2440 and testing numerous D/A's taking in to consideration performance, solderability, cost, availability and the winner is LTC 1655 by a long shot, is even available in a DIP with 16 bits more than you need for any Rb and if you want 20 bits, dithering is an option. My testing consistently shows with OCXO's aging that will in most cases allow operation of an OCXO for 3 years with out intervention. To top it off the LTC1655 cost less than $ 10. Testing the old AD 1861 was an eye opener but considering what its purpose was and its time the best choice. Bert In a message dated 12/30/2011 4:24:37 P.M. Eastern Standard Time, timen...@n4iqt.com writes:
The DAC and it's voltage reference looks to be the weak link in the digital control and the "simple" goal. The CPU I mentioned before on closer look doesn't have a good DAC. The 20 bit TI DAC1220 looks better but not sure you can find it in the same package as the CPU. The cheap Rb standards with digital control would not need a DAC and maybe this points to a simpler GPSDO that doesn't control the XO with analog but corrects it with a DDS but again finding them both in one chip is the problem. I have seen OCXO and DAC in the same package and even the DDS and OCXO combined but they didn't fit the simple goal. Not even sure how good they were. I know they are hard to find. Stanley _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
