Universal Trigonometric Function Converter

“The AD639 is a general trigonometric function generator where the output is a scaled ratio of two sines, where each sine has tunable parameters. The package on this one was another ceramic case with a gold cover that was held on by solder. Heating the case and pushing over the solder revealed a very clean chip with a seemingly small number of transistors. No markings were found on the chip other than the model number and Analog’s logo.”

Source: http://microblog.routed.net/2007/03/30/ic-friday-analog-devices-ad639/

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