Selecting an op amp...specification questions...output capability / GBW / etc

[Skimask]

Trying to select an op-amp that'll do what I'm needing.

- Dual supply capable, e.g. +12v & -12v (or 15v if I can find one)
- Source at most 120mA at the output with the output capable of staying fairly close to the rails, but by no means is it a requirement to get right to them...
- Maximum gain will be about 10, no more than that
- Maximum frequency input of about 20khz

Looks like the TCA0372 will handle what I need.

Trying to understand GBW now.
The datasheet says GBW is .7Mhz thru the range of the device.  If I'm reading it right, this means that at unity gain, I can feed a 700khz signal thru it without getting too much distortion.  Similarly,  if I'm trying to get a gain of 10, the maximum freq the opamp will work at is about 70khz....   Freq of input X gain = GBW...
Is it that simple?  I realize there's a bit of a fudge factor in anything like this (e.g. the GBW will likely vary with varying conditions, power supply, input impedance, output impedance, etc).  So, is that simple  Freq X gain = GBW  a decent rule of thumb to go with?

[w2aew]

Yes, that's the simple rule of thumb.  But of course, the devil is in the details.  One more little point, the BW is the point where the response is down 3dB. The specs hold true under the conditions specified.  There are usually characteristics curves that will show how some parameters change under different operating conditions. At the end of the day, it is always a good ideas to build and test, test, test.

[Skimask]

Good enough for me.  It's not a critical item.  The biggest requirement I'm having an issue with is the max 120mA load and trying to get a decent signal output at the same time.

[w2aew]

Agreed - +/-120mA output, and swinging close to rail-rail - that's a tall order.

[Skimask]

meh...close is a relative term too.
If I get 10v on the output with 15v input at the 120mA load, I'll be happy.  Anything more than that is icing on the cake...