• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 17 subscribers
  • Views 1296 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

RF430FRL152H: Amplifier in GSR monitoring circuit using NFC sensor transponder

JooHo Yun
Prodigy 30 points
Part Number: RF430FRL152H
Other Parts Discussed in Thread: LMP2231,

Hi,

  I want to know why the amplifier(U1 LMP2231) was used at sensor components which consist of a galvanic skin response(GSR) sensor and a thermistor. 

I've designed a GSR sensor using RF430FRL152H.

When I searched for information about it, I saw a paper named 'Designing and evaluating an NFC-enabled bio-patch for medical and health & fitness applications' which is published at Texas Instruments. 

In the paper, they designed circuits like the pictures but I wonder why they used a non-inverting amplifier(U1 LMP2231) in the circuit.

I think, without an amplifier, it is enough to work because RF430FRL152H has its own ADC amplifier.

Would you pls tell me the reason to use the amplifier and how does it work in the circuit? 

Thanks

JooHo

  • 0
    TI__Mastermind 18265 points

    Hello JooHo,

    the colleagues who developed this circuit are no more available so I also have to guess. A reason could be a higher input impedance and also a low sensor voltage which is save to use.

    I noticed that the circuit has a wrong component in the diagram. The diode (1N3879) should be a voltage reference with 1.225V (LM4041CIM3-1.2).  

    Best regards,

    Helfried