# High Speed Op Amp Query

#### Wendy

Joined Mar 24, 2008
22,145
What is a good cheap modern high speed op amp? It has to have basic DC characteristics, but more than basic stability isn't important DC wise. Cost is important, as is availability. Think a modern 741 (although dual or quad is better).

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OK, started the table, which will likely always be a work in progress. This is obviously very preliminary. Keeping in mind we want this fit a standard page, what other specs are needed? Word of mouth on specs will be accepted.

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#### SgtWookie

Joined Jul 17, 2007
22,210
Have you looked at LF353's? Wide bandwidth (4 MHz) JFET input dual opamps. Cheap. You won't find it at your local Radio Shack, but DigiKey, Mouser, and many other places stock 'em. From Mouser, you could get 10 of 'em for $3.10 + shipping. Checked over at Jameco, for quantities of 5 or more you can get 'em for around$0.17 each.

#### Papabravo

Joined Feb 24, 2006
13,923
I'm kinda partial to the TL081/TL082/TL084 and its cousins the TL071/TL072/TL074

#### SgtWookie

Joined Jul 17, 2007
22,210
I'm kinda partial to the TL081/TL082/TL084 and its cousins the TL071/TL072/TL074
The LF353 is similar to the TL072, but the TL072's BW is 3MHz, whereas the LF353 is 4MHz.

If you need more bandwidth, take a look at LT1057's by Linear Technology.

If you need LOTS of bandwidth, check out National's LM6152; a dual opamp with rail/rail inputs & outputs and 75MHz GBW product. They'll set you back about $3.50 each in small quantities. #### Audioguru Joined Dec 20, 2007 11,249 The TL071, TL072 and TL074 opamps are the same as the TL08x but are selected for low noise. They have FET inputs so have almost no input bias current and very low current noise. They have a bandwidth of 100kHz at full output. But they have the problem of older FET-input opamps called "opamp phase inversion". #### Attachments • 15.3 KB Views: 248 #### Papabravo Joined Feb 24, 2006 13,923 The TL071, TL072 and TL074 opamps are the same as the TL08x but are selected for low noise. They have FET inputs so have almost no input bias current and very low current noise. They have a bandwidth of 100kHz at full output. But they have the problem of older FET-input opamps called "opamp phase inversion". Absolutely correct. I have also been burned by a similar problem with an LM324 (PNP inputs), used in a single supply process control application as a unity gain follower, where the input went below the negative rail, and the output went to +Vout(MAX). The quick and dirty fix was a schottky diode clipper on the input. One problem with the OP is that we lack a precise definition of high speed. Cheap and available we understand. #### SgtWookie Joined Jul 17, 2007 22,210 That's just one of the nice things about the LT1057. It's protected against phase reversal. #### Attachments • 146.5 KB Views: 163 Last edited: #### Papabravo Joined Feb 24, 2006 13,923 That's just one of the nice things about the LT1057. It's protected against phase reversal. OK, but they are not cheap. From Digi-Key,$4.50 and $8.75 each in QTY. 1 for the available parts and$2.95 for the SOIC with minimum order quantity of 600 where they only have 282 available. What a laugh riot, I guess if you order 600 they'll ship what they have and back order the rest.

Spot check of other prices for DIP parts
Rich (BB code):
TL082 is $0.44 TL072 is$0.50

#### jpanhalt

Joined Jan 18, 2008
9,686
What do you think of the LM6171? It's cheaper than the THS4303 and has better slew rate than the LM6152, plus it has a wide supply voltage range . Maybe it's a 928 S4 Porsche?

John

#### Wendy

Joined Mar 24, 2008
22,145
Something I might do (with a little help from my friends) is draw up a sample comparison chart for op ams under a \$1, with things like unity gain, power supply range, slew rate (I like slew rates for some reason). I might add it to my first post for easy comparisons. What other specs do you think would be needed? Some of the more popular expensive units could be added at the bottom, for comparison. I can't be the only guy to allow himself to get out of date on some of these specs.

#### jpanhalt

Joined Jan 18, 2008
9,686
Here are some suggestions:
Slew rate
Unity gain frequency
Input bias current
Power supply (range)
Input type (FET or bipolar) - may be irrelevant given bias current
Voltage or current feedback
CMRR (?)
Unit price (use Digikey and/or Mouser)
Available packages