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TDC1011: I can not see any amplification at LNA output

Prodigy 30 points

Replies: 3

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Part Number: TDC1011

Hello,

I am woriking with TDC1011 in a project where 1MHz ultrasonic transducers will be used to measure some media concentration.  

However, at this point of the project I replase the ultrasonic signal by a 1MHz sine wave from a GFG-3015 generator. The point is that we are using the TDC1011 only for signal amplification. I mean that we don´t use it to measure the time of flight. We are only interested in the LNA and PGA amplifiers. 

So looking to the datasheet, I write a 0x10 value in TOF_1 register focusing by the moment on the LNA (I don´t touch any other register). I see on the oscilloscope a 1MHz sine wave on RX pin, but however no signal is on LNOUT pin. What is going on?

Could someone tell me what am I missing?

Any help will be appreciated. 

Thanks in advance. 

3 Replies

  • Hi Aitor,
    Our TDC specialist is currently out of office, and will be able to respond next week. Thanks for your patience.
    Akeem Whitehead // Texas Instruments // ASC-SENSING-CSPS // Applications Engineer
    Visit our Ultrasonic Sensing FAQ page for additional information.
  • In reply to Akeem Whitehead:

    Hello,
    Is there any TDC specialist available? Some help would be very appreciated?

    Thanks again.
    BR.
  • Aitor,

    As shown in Figure 16(In Datasheet: www.ti.com/.../tdc1011.pdf), the external capacitor, CIN, should be placed between the transducer and the input pin. This provides an in-band gain of CIN/CF, where CF is the on-chip 30-pF feedback capacitor.
    Also the LNA or PGA cannot be used without configuring the Rx path from the transducer.

    ---------------------------------

    Bharat Aravamudhan

    Sensor Signal Conditioning Applications

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