single ended to differential opamp

Paolo Geriniz

Other Parts Discussed in Thread: DRV134

Hello,

our goal is to convert a single ended output (+/- 9V) coming from an high dynamic sensor into a differential output.

This should help when sensor is placed far away from the digitizer (24bit).

Considering the low BW of the sensor < 100Hz which fully differential op amp coming from TI is most suitable for our application?

Regards,

Paolo

over 9 years ago

0 Thomas Kuehl over 9 years ago

TI__Guru* 93105 points

Hi Paolo,

Are you intending to drive the inputs of the 24-bit A-to-D converter directly from the differential op amp outputs? If so, which converter?

If you do plan to use a fully differential input, differential output, op amp in your application those amplifiers are supported on TI's High Speed Amplifiers E2E forum. We may end up shifting your inquiry to it.

Regards, Thomas

PA - Linear Applications Engineering

0 Paolo Geriniz over 9 years ago in reply to Thomas Kuehl

Prodigy 120 points

Hi Thomas,

Thanks for your quick answer!

Our goal it’s not to design a front end to drive an adc inputs.

Imagine a sensor with a differential output placed far away with 100m of cable, cable which ends up on the recorder inputs.

The recorder can be any of those on the market, but 24 bit are mandatory because of the high dynamic of the sensor.

So basically we don’t know which will be the front end and the adc.

Our goal it’s to transform the output of the sensor (at the moment it is single ended) into differential.

We believe that the differential output can help to reduce the noise injected on the cable.

I hope to have been clearer.

0 Thomas Kuehl over 9 years ago in reply to Paolo Geriniz

TI__Guru* 93105 points

Hi Paolo,

Thanks for the explanation. Although two op amps can be configured in a couple of different single-ended input, to differential output configurations, those usually have to be tailored somewhat for the application. For example you mention driving 100 m of cable, which very likely will appear as a large capacitive load at each output. Since most op amps have a limit as to how much capacitance they can drive and remain stable, stabilization circuitry must be added when that limit is approached.

A solution that I might suggest is to consider an audio-balanced line driver such as the DRV134. It is optimized for single-end input, differential output, line driver applications and it is rated with very low THD. Typically, it drive a load capacitance up to 1 uF and most 100m lines should be a fraction of that . You can find the DRV134 datasheet here:

Be sure the DRV134 has sufficient bandwidth to cover your application requirements.

Let me know if this gets you any closer to a solution.