• State TI Thinks Resolved
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 45 views
  • Users 0 members are here
Support feedback
Options
Options
Related

THS4503: Single-Ended to differential conversion

Subhajit Sen
Prodigy 70 points
Part Number: THS4503
Other Parts Discussed in Thread: TINA-TI

Tool/software:

I am trying to design a singe-ended to differential amplifier to convert a single-ended input to a differential output to drive an ADC.

I am using THS4503 and the circuit is shown below. The ADC provides me a 1.5V CM (common-mode) voltage that I apply to

THS4503 as shown. The supply is 10V and single-ended. The input is a 1V peak-peak signal at 1 MHz. However, I do not see any

output. The input and output common mode voltages are within the data sheet specs. However,I do not see any output. Even if I capacitively couple the input signal there is no output. What is the issue ? 

Note that the output shows a sine wave but the amplitude is 0 if you see the scale.

  • 0
    TI__Mastermind 22704 points

    Hello Subhajit,

    Please see the attached TINA-TI file.  I do believe I have a working version of your circuit.  My advice would be to use the 'meter' device for measuring each output independently and the differential voltage measurement (or voltmeter) for measuring the differential VOUT of the output.

    THS4503_debug.TSC

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    Prodigy 70 points

    Thanks for your reply. Yes your circuit does appear to work tho' my circuit does not work consistently.  But my main issue now is: if I apply the input signal using capacitive coupling using a 1u or 10u series capacitor the circuit shows instability. Also the common mode output voltage is not preserved. I have seen some application circuits using THS4503 that have capacitive coupling. How do I resolve this ? Regards.

  • 0 in reply to Subhajit Sen
    TI__Mastermind 22704 points

    Hello Subhajit,

    I am not sure what error is presenting in your circuit.  I was able to add-in 1uF AC coupling capacitors with no issue.  Common mode output voltage is also preserved in this simulation file.

    THS4503_debug_AC_Coupling.TSC

    Best,

    Alec