Other Parts Discussed in Thread: LMV861, , THS3217, THS3215, OPA356, LMV7219
Hi,
i'm trying to find a suitable substracting OpAmp that will allow me to substract two DC signals that represent the output power of a PA, these signals are Vdet &Vref (coming from PA diodes)
i want to substruct between them and to compare via comparator to the value 400mV
the thing is that the PA works in pulses, thus i want that the substructing time will be for e.g. 20nSec while the pulse is about less than 100nSec
i though that i need to look for high slew rate and little setting time but things didn't work for me. i add here few simulation pics
i simulated with LMV861 the result is ok but its taking too much time.
input is 0.8V as Vdet to V+ 0.4V to V- as Vref
below is
below is OPA858, fast enough but substracting result not really equels to Vdet-Vref , and why i need this 50 ohm to stabalization
input is 600mV to V+ to V- its 400mV
i would be glad if you could recommand me to chose the right parts for this "simple" issue, we will going to make 1000 per year.