NE592 video amplifier

[rbyrne15]

Hi,

Has anyone had any experience with the NE592 video amplifier IC? I'm trying to amplify a square wave at 1.5 Mhz, but the output is very distorted. The distortion appears not to be harmonic distortion, but phase distortion.

I have built the circuit on a breadboard and have now soldered all my connections on a circuit board, but the results seem no different. The circuit is based on the manufacturer's "basic configuration" schematic.

Any help anyone could provide would be greatly appreciated.

Thanks,

Richard.

 

[benta]

Sounds reasonable. According to the datasheet you'll have 50 degrees of phase shift already at 10 MHz.
This part is ancient, why not check with National, for instance.
They have very high speed opamps (LMH66/67xx series).

Regards,

Benta.

 

[jimkirk]

It's been a while since I've used one. What is the input amplitude? Gain setting? Power supply voltages? How are you loading the output?

The spec sheets from OnSemi and NXP show about 20 degrees (not 50) phase shift at 10 MHz, but note that at 200 MHz the phase shift is about ten times that. That translates into a simple constant time delay of about 6 nS, not something that should cause significant phase shift error. (Look at the propagation delay spec.)

The 592 has plenty of bandwidth, 40 MHz or more, depending on gain. A 1.5 MHz square wave should look pretty good. What are you using for a gain network?

As Benta asks though, why are you using this part? It has some nice features like differential input and output, but it's a dinosaur compared to many modern video opamps.