That's not what Analog Devices says. They quote 33% of the reference clock (up to 125MHz, which is what I see on the eBay modules). So that's 40MHz right there. Really not trying to lead you down a blind alley. Cheers, Bob On Sun, Oct 11, 2015, at 11:22 PM, David C Brown wrote: > The AD9850 sine wave generators are just that - sine wave generators.=20 > They > quote a square wave up to 5MHz which is not good enough. >=20 > On 12 October 2015 at 03:33, Bob Blick wrote: >=20 > > Hi David, > > > > Have you looked the plethora of AD9850 DDS sinewave generators? They > > have a comparator for squarewave output. I don't know what your spec is= , > > but you could put a toggling flip-flop on the comparator output if you > > need better duty cycle accuracy than the comparator itself (if you can > > lose the upper octave). > > > > Best regards, Bob > > > > On Sun, Oct 11, 2015, at 11:04 AM, David C Brown wrote: > > > I am looking for a module to generate logic level square wave up to a= t > > > least 20MHz (50 would be better) within a $100 budget. There are a > > > number > > > of items on eBay but none have them seem to have a proper spec. Any > > > recommendations from experience? > > > > > > -- > > > __________________________________________ > > > David C Brown > > > 43 Bings Road > > > Whaley Bridge > > > High Peak Phone: 01663 733236 > > > Derbyshire eMail: dcb.home@gmail.com > > > SK23 7ND web: www.bings-knowle.co.uk/dcb > > > --=20 http://www.fastmail.com - Access all of your messages and folders wherever you are --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .