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THP210: Differential-to-single-ended amplifier.

Part Number: THP210
Other Parts Discussed in Thread: INA849, OPA211

Tool/software:

Hi, do you have a differential to single ended amplifier similar to AD8129 from Analog Devices?

Thank you.

  • HI Fabio,

    The AD8129 is a differential receiver amplifier with 270-MHz high-bandwidth amplifier (high-speed). 

    I will need to refer your question to the High-Speed amplifiers product line.

    Thank you and Best Regards,

    Luis

  • Hi Luis, on my application I need only up to 20Mhz.
    Can you forward the question, or I need to open a new topic?

    Thank you.

  • HI Fabio,

    You can achieve differential to single-ended conversion with an op-amp configured as a difference amplifier using discrete resistors.  If you have strict accuracy, CMRR requirements, you could consider using a matched resistor network such as RES11A00 or other match resistor networks depending on the voltage or gain requirements.  If you have a 20MHz bandwidth requirement, you will need to choose an op-amp with higher BW than 20MHz.

    https://www.ti.com/lit/ds/symlink/res11a.pdf

    Difference amplifier Application Note:

    https://www.ti.com/lit/an/sboa274a/sboa274a.pdf

    Beyond the 20MHz BW requirement, do you have any specific supply requirements? what is the input common-mode voltage range and differential voltage range requirement? What is the output voltage range and/or gain requirement? Any strict accuracy requirements? do you have any strict input impedance requirements? 

    Thank you and Regards,

    Luis

  • HI Fabio,

    The INA849 is an instrumentation amplifier with relative high bandwidth.  If you require high-input impedance, depending on your input common-mode range and voltage supply requirement, the INA849 could work for you offering a BW of 28-MHz at G=1.  Leaving RG unpopulated will set the device to a G=1

    However, we would need to check the input-common mode range and supply requirements, and confirm/verify if the INA849 meets the supply, input voltage range and output voltage range requirements.

    Beyond this, if you don't require a very high input impedance, the OPA211 (or other amplifier with GBW > 20-MHz, depending on accuracy and voltage supply requirements) configured in a difference amplifier configuration, with discrete resistors (or a matched resistor network) could work as well.

    Thank you and Kind Regards,

    Luis

  • Thank you Luis, INA849 seems to be a good alternative.

    I have available +-5V, and the input is a current sensor that provide a Wheatstone bridge with +-60mV range also feeded in the same power supply.

    The ref input will be useful to compensate any offset from the Wheatstone bridge.

  • Thank you Fabio, 

    Provided that the INA849 is configured with Gain=1, the device will meet the small-signal bandwidth requirement.  Below is the gain vs bandwidth specification for the INA849.

    If the INA849 powered with ±5V supplies, and the Wheatstone bridge is powered with the same supplies, with a ±60mV signal centered at 0V common-mode, this will work well within its linear range.

    Below is a snap shot of the Vcm vs Vout Instrumentation Amplifier calculator, showing the device is in range.

    https://www.ti.com/tool/ANALOG-ENGINEER-CALC

     

    Many Thanks,

    Kind Regards,

    Luis