On Saturday 08 April 2006 04:40 pm, John Doty wrote: > > However, your other example of the op amp with the output grounded has > > knocked me down. Very smart application!. > > Ran into that one about 30 years ago when I was a grad student at > MIT. Mike Shao, another grad student (now Mr. Optical Interferometry > at JPL) had gotten a piezoelectric actuator driver from somebody but > couldn't figure out the strange topology, asked me to explain it to > him. Cascode transistors on the low voltage rails carried the current > out from the opamp to high voltage rails, where there were mirrors, > making a transconductance amplifier that had an output swing of > several hundred volts, just the thing to drive a piezo. I don't know > who came up with this.
While I'm sure Linear Tech. did not come up with, it is explained here for anyone interested: "How to Ring a Phone with a Quad Op Amp" Summary: http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1042,C1031,C1061,P1266,D4338 Detailed description: http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1045,P1657,D4174
