Re: current-mode opamps

On Tue, 26 Feb 2008 20:48:30 -0800, "Jim Thompson"
<To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> wrote:


"John Larkin" <jjlarkin@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:4te8s3h7h4037d3mgmqcroh4a9au5npndk@xxxxxxxxxx
On Tue, 26 Feb 2008 11:29:06 +0100, Fred Bartoli <" "> wrote:

John Larkin a écrit :
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


Are your supplies symmetrical or do you use it single supplied?

+7.5 and -5.5, so we can make anything from TTL to ECL output levels.
But that shou;dn't affect input impedance symmetry.

John


Not so dummy, when you screw the TTL logic with wrong level you screw your
output as well. What planet are you from?



We speak English here. What planet are you from?

John


.

Relevant Pages

  • Re: current-mode opamps
    ... good large-signal performance. ... transient response but doesn't much affect the apparent 10 pF input ... Today's experiments suggest that the "fake capacitance" at the THS3201 ... when you screw the TTL logic with wrong level you screw your ...
    (sci.electronics.design)
  • Re: current-mode opamps
    ... good large-signal performance. ... transient response but doesn't much affect the apparent 10 pF input ... Today's experiments suggest that the "fake capacitance" at the THS3201 ... But that shou;dn't affect input impedance symmetry. ...
    (sci.electronics.design)
  • Re: Citation II Rebuild Project
    ... transient response, in terms of how we measure it with lab ... Adding excessive capacitance may indeed alter the ... bottom end of the amp to the detriment of the top. ... PS sag will be slower for the amp with the bigger cap. ...
    (rec.audio.tubes)
  • Re: Citation II Rebuild Project
    ... transient response, in terms of how we measure it with lab ... Adding excessive capacitance may indeed alter the ... bottom end of the amp to the detriment of the top. ... PS sag will be slower for the amp with the bigger cap. ...
    (rec.audio.tubes)