Re: current-mode opamps

On Mon, 25 Feb 2008 15:15:33 -0800, Tom2000 <abuse@xxxxxxxxxxxx>
wrote:

On Mon, 25 Feb 2008 13:53:12 -0800, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

On Mon, 25 Feb 2008 09:44:33 -0800, Tom2000 <abuse@xxxxxxxxxxxx>
wrote:

On Sun, 24 Feb 2008 19:07:18 -0800, John Larkin
<jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:



At G=2, 100 ohm load, they suggest that both resistors be 715 ohms for
good large-signal performance. Playing with the resistors changes
transient response but doesn't much affect the apparent 10 pF input
capacitance.

The eval board, and the S-params setup, effectively drive the ni input
from a 25 ohm source. The frequency response curves are unclear on
what the generator source impedance may be. They give inverting and ni
curves small-signal, but the large-signal stuff is all inverting. Are
they trying to hide the actual performance?

TI is beginning to disappoint me.

John


John, have you had a chance to compare the TI CFBs with the AD
versions?

(Great thread, by the way...)

Thanks,

Tom


The ADI parts are great if you don't need a lot of voltage swing. We
use AD8009's, 8014's, 8001's, all great parts without quirks.

The TI's have insane slew rates and bandwidth with +-7.5 or even +-15
rails, like nothing else I know of.

TI also makes some insanely fast fixed-gain amps, THS4302 and 4303.

John

Thanks, John. Great info. I'm keeping this whole thread for
reference.

Tom

Today's experiments suggest that the "fake capacitance" at the THS3201
input is different depending on the polarity you happen to be slewing.
Even more fun!

We're looking into output stages that use discrete GaAs fets.

John

.

Relevant Pages