# Op Amp with slew rate of 10,000 V/micro second exist?

Discussion in 'General Electronics Chat' started by ping222, Feb 5, 2014.

1. ### ping222 Thread Starter New Member

Nov 7, 2013
13
0
Hello,

I would like to amplify a 2 GHz sinusoidal voltage signal (0.22 V peak to peak) using an operational amplifier. The gain I would like from the operational amplifier is about 5, that is, I would like a voltage output from the amplifier to be approximately 1 V peak to peak given the input. The problem is I can't seem to find an op. amp. with a slew rate that can give me the desired performance. The slew rate I require can be calculated for a sinusoid to be 2*pi*f*Vpp where,

f is the frequency of the signal (2 GHz in my case)
Vpp is the peak to peak output voltage required (1 V in my case).

Using this formula I require a slew rate of 12,566 V/micro second. I can't seem to find anything out there that exists that can go this fast. I don't have much experience with op. amps. Do they currently exist to meet my specifications? Thanks in advance for any feedback,

Regards,

Ping.

2. ### atferrari AAC Fanatic!

Jan 6, 2004
2,612
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Most probably not that fast but there were some that National used to call in their books "dam fast" op amps.

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3. ### LvW Active Member

Jun 13, 2013
674
100
Ping22, try to find a suitable amplifier in current-feedback topology (CFA).
I know they exhibit slew rates of several thousands of volts/µs.
Such amplifiers can be used and wired like conventional opamps.
The only point to be considered is that the feedback resistor must be larger than a specified minimum.

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4. ### alfacliff Well-Known Member

Dec 13, 2013
2,449
428
does it need to be an op amp? if not, there are sevral MMIC's that will amplify with more gain than tha at 2 ghz. check out MINICIRCUITS LABS site for info.

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5. ### #12 Expert

Nov 30, 2010
16,031
6,542
Basic rule: The more parts in a stage, the slower they are, even if for no other reason than parasitic capacitance and inductance. One or two transistors stands a better chance of going fast than 50 or 100 transistor on an integrated chip.

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Apr 5, 2008
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Last edited: Feb 5, 2014
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7. ### RichardO Well-Known Member

May 4, 2013
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I think that you are off by a factor of 2. Slew rate is 2*pi*Vpeak.

Even at "only" 6,000 v/us you are in a lofty realm. You should consider a video amp or ADC driver instead of a true op-amp. Maybe one like this:

http://www.linear.com/product/LTC6417

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8. ### ping222 Thread Starter New Member

Nov 7, 2013
13
0
Thanks guys for all of that, I will look into it and post what I find. With regards to 'RichardO' post, yeah I am pretty sure it is sinusoid peak to peak voltage that is required in the 2*pi*f*Vpp calculation. Therefore would not be off by a factor of two in that case.

9. ### #12 Expert

Nov 30, 2010
16,031
6,542
Typo. It's 2 Pi F Vp
not Vp-p

10. ### crutschow Expert

Mar 14, 2008
12,561
3,078
I have to weigh in. It's 2*pi*f*Vp as shown here. It's calculated as the peak value of the derivative of the sinewave or d/dt (Vp*sin(2$\omega$t)) = 2*pi*f*Vp * cos(0) = 2*pi*f*Vp.