On Tue, 10 Nov 2009 01:58:26 +0000 (GMT), carzr...@optonline.net wrote: > I have a problem with an opamp at work and was hoping someone may have some > insight. > > This particular opamp is opa2132 from TI, and has slew rate of about 20 > V/us. It's driven by a sine wave at 5 kHz. The gain is sufficiently large > that the opamp is driven into saturation by the sine wave and the slew rate > limited edges are very obvious. The rails are +/- 7.5V and it is able to > drive to about +/- 6V. It is connected to an old CD40106 schmitt trigger > inverter. > > Here's the rub. The opa2132 doesn't run anywhere near the advertised > 20V/uS spec. I see, at best, around 15V / 12 uS, or about 1 or 2 V/ uS. > Not even close to spec. I am fairly certain that the schmitt trigger > responds poorly to the very slow edges from the opamp. I happen to use 2 > channels of this, and the phase relationship is very important - but it > gets destroyed through the schmitt trigger. > > I've gone as far as removing all loads from the opa2132, and it doesn't > change the slew rate. The data sheet has a drawing with 'large signal step > response', and it shows the part slewing around 15 or 20V in 1 uS. Not > bad. So what have I done wrong? They do claim it's with a gain of -1, but > I don't see how that has anything to do with it.
What's the op-amp's gain-bandwidth product? Peter -- Peter Brett <pe...@peter-b.co.uk> Remote Sensing Research Group Surrey Space Centre _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user