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Wideband amp circuit

L

Luke Simmons

Jan 1, 1970
0
Can someone please point me to a circuit diagram for a wideband amp
with the following specs or there about? It will be used with a signal
generator only (basic and modulated waveforms), not for
communications, etc.

100Hz to 2MHz bandwidth
40Vpp output into 50 ohms

Thank you for any assistance.

Luke Simmons
 
R

Robert Baer

Jan 1, 1970
0
Luke said:
Can someone please point me to a circuit diagram for a wideband amp
with the following specs or there about? It will be used with a signal
generator only (basic and modulated waveforms), not for
communications, etc.

100Hz to 2MHz bandwidth
40Vpp output into 50 ohms

Thank you for any assistance.

Luke Simmons
DC frequencies.
 
W

Winfield

Jan 1, 1970
0
Luke said:
Can someone please point me to a circuit diagram for a wideband
amp with the following specs or there about? It will be used
with a signal generator only (basic and modulated waveforms),
not for communications, etc.

100Hz to 2MHz bandwidth
40Vpp output into 50 ohms

That's +/-20V at +/-400mA = 8W peak, right? And it requires
a 250V/us slew rate. The APEX PA09 amplifier can do that if
compensated for high-frequency G = 100 (with a loop-gain
reducing R + C across the + and - input pins).
 
T

tlbs101

Jan 1, 1970
0
Can someone please point me to a circuit diagram for a wideband amp
with the following specs or there about? It will be used with a signal
generator only (basic and modulated waveforms), not for
communications, etc.

100Hz to 2MHz bandwidth
40Vpp output into 50 ohms

Thank you for any assistance.

Luke Simmons

One of these with an output current booster will do the trick, plus
it's much cheaper than anything from Apex (although Apex products are
great, too):
http://focus.ti.com/docs/prod/folde...lpos=Middle_Container&lid=Alternative_Devices
or, the app notes in the datasheet show how to parallel 2 of them for
double the current (which meets your requirement). And 2 OPA552s are
still cheaper than 1 Apex amplifier.

..
 
W

Winfield Hill

Jan 1, 1970
0
One of these with an output current booster will do the trick, plus
it's much cheaper than anything from Apex (although Apex products are
great, too): http://focus.ti.com/docs/prod/folders/print/opa552.html
or, the app notes in the datasheet show how to parallel 2 of them for
double the current (which meets your requirement). And 2 OPA552s are
still cheaper than 1 Apex amplifier.

The Buur-Brown opa552 is a nice part, able to be powered
from +/-30V supplies. But sadly it's got a slow slew rate
of only 24V/us. If Luke wants 40Vp-p at 2MHz, then he'll
need S = 2pi f A = 251V/us slew rate, as I said, which is
10x faster than the opa552. Sorry.

One part that might do the trick is Analog Devices' ad815ay.
This can only be powered from a maximum of +/-15V, but it's
a dual amplifier and when used in bridge configuration it
can deliver +/-25V at +/-500mA, with a 900V/us slew rate
(I was able to pick up a supply of their 15-pin SIP heat-
sink tab-style power package before they discontinued it).
 
F

Fred Bloggs

Jan 1, 1970
0
Can someone please point me to a circuit diagram for a wideband amp
with the following specs or there about? It will be used with a signal
generator only (basic and modulated waveforms), not for
communications, etc.

100Hz to 2MHz bandwidth
40Vpp output into 50 ohms

That's just a simple CE with a simple simulated inductor step-down
load...piece of cake. Take your question to the Basics ng.
 
W

Winfield

Jan 1, 1970
0
That's just a simple CE with a simple simulated inductor step-down
load...piece of cake. Take your question to the Basics ng.

Nowadays, with high-performance DC wideband amplifiers
available, it's tempting to use one of them instead of a
traditional class-A amplifier. But Luke could consider
a class-A amp amplifier running with a Vce of roughly
25V and a current of roughly 500mA, which would have a
quiescent power dissipation of about 12.5 watts. Then a
100-to-900mA collector-current excursion would deliver
+/-20V into a 50 ohm load. The collector-supply inductor
would have to be greater than 80mH (that's pretty large!)
for a 100Hz low-freq rolloff. The output-node capacitance
would have to be under 1600pF for a 2MHz high-frequency
rolloff. No doubt the large 80mH choke would deliver some
of that, so a second smaller series inductor would be wise.
There's more to consider, emitter degeneration, input gain,
class-A biasing, etc., but it's evening and duty calls.
 

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