Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!gem.mps.ohio-state.edu!rpi!batcomputer!eacj From: eacj@batcomputer.tn.cornell.edu (Julian Vrieslander) Newsgroups: sci.electronics Subject: Looking for digitally controlled attenuator, with 0 - 120 dB range Message-ID: <8994@batcomputer.tn.cornell.edu> Date: 4 Oct 89 00:20:32 GMT Reply-To: eacj@tcgould.tn.cornell.edu (Julian Vrieslander) Organization: Cornell Theory Center, Cornell University, Ithaca NY Lines: 22 Some time ago there was a discussion in this group on how to implement a digitally controlled attenuator. I put in a plug for the Analog Devices AD7111, a logarithmic D/A convertor that attenuates an analog input signal over the range 0 to -88.5 dB, according to a value latched into an 8-bit data word. But now I find that I need to build a digitally controlled attenuator with a range of 0 to -120 dB! I thought of cascading 2 AD7111's, but it looks like the noise specs are not good enough. The best alternative that I have found is the MTA1537 Voltage Controlled AGC/Attenuator from VCA Associates (Canoga Park, CA). This is a low noise, low distortion IC optimized for HiFi gain control applications. Controlling it digitally will require an D/A stage to supply the control voltage. If anyone knows of equivalents or alternatives to the MTA1537, I would appreciate hearing about them. The input signal will be 7 Vrms, with 10 Hz to 10 kHz bandwidth. -- Julian Vrieslander Neurobiology & Behavior, W250 Mudd Hall, Cornell University, Ithaca NY 14853 UUCP: {cmcl2,decvax,rochester,uw-beaver}!cornell!batcomputer!eacj INTERNET: eacj@tcgould.tn.cornell.edu BITNET: eacj@CRNLTHRY