• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 49 subscribers
  • Views 148 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

UA733: Applications question

Nicolas Professi
Prodigy 10 points
Part Number: UA733

Hi, i am doing research about the history and operation of uA733. I found an application note of the NE592 which is a similar circuit. 

I don't understand what is the purpose of a video amplifier, i read that these devices were used in amplification of low level differential signals of the heads of floppy disk readers, is that correct?

Also, i don´t see yet how this amplifier works at 120Mhz, my understanding was that without a dominant pole, at high frequencies the phase change to 180 degree changing the negative feedback to an unstable positive feedback, but in this case it does not have a dominant pole (improving the bandwidth), but how they make this device stable at high frequencies?

Thank you for helping me to figure out this things.

  • +1
    TI__Expert 7660 points

    Hi Nicolas,

    The device datasheet does highlight the application you are referring to, but the device is a general video amplifier. As for your second question, the device does have a dominant pole in its frequency response as it has specific bandwidths at different gains. If there was no pole in the system, its bandwidth would be infinite. This pole is what also causes a phase shift in the system. As the system phase shifts more due to an additional pole at higher frequencies, it can reach a point where the device is unstable and oscillates. I recommend a great video series that discusses this topic in much more detail and gives great examples. The series is called TIPL (TI Precision Labs found here) and it covers a range of topics specific to amplifiers, the topic that relates to your question is under the stability topic. 

    Best Regards,

    Ignacio