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I have a differential input of 2-V and it apply to TLV-2221 op-amp with unity gain of one, but the output shows the zero voltage waveform,can anyone explain why it happens? here i am attaching the screenshots of my simulation. enter image description here

enter image description here

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  • \$\begingroup\$ Get rid of the yellow waveform - it's cluttering the view. \$\endgroup\$
    – Andy aka
    Commented Sep 4, 2020 at 8:34
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    \$\begingroup\$ Very-much related to this earlier question: electronics.stackexchange.com/questions/519889/… \$\endgroup\$
    – Andy aka
    Commented Sep 4, 2020 at 8:40
  • \$\begingroup\$ yes,this question was related to that question ,with different resistor values we observe the output waveform differently,but all four resistors are with same value in tlv2221(unity gain),then theoritically we got the same output as output of amc1301 ,but in simulation it doesn't show like,what is the mistake here \$\endgroup\$
    – maneesha
    Commented Sep 4, 2020 at 8:54
  • \$\begingroup\$ What is the common mode voltage of the red signal? \$\endgroup\$
    – The Photon
    Commented Sep 4, 2020 at 13:40

1 Answer 1

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Let's start at the beginning. The gain of the AMC1301 is 8.2x. The input signal range is + - 250 mV. Thus, a + -2 V signal is expected at the output. egy

kettő

If we needed the full range, the 3.3 V supply voltage would be little for the 4 Vpp signal. Then we need to use a supply voltage of at least 5V. However, a supply voltage of 3.3 V is sufficient to solve the specific task. The next problem is that the input voltage of the TLV2221 can be between 0 and 2V at a supply voltage of 3.3V. The Vp signal exceeds this value. három

négy

öt

So we definitely have to choose a different amplifier. Select the same one you used for the older similar task.

öt1

The input DC offset voltage determines our operating points throughout. The operational amplifier must be set so that half of the supply voltage is at output. (For maximum dynamics.) The input already has a 1 V offset voltage. To do this, approx. 0.5 V must be added plus (VREF). We will do this by building a divider from two resistors with a voltage of 550 mV and the internal resistance 10k Ohm: enter image description here

Thus we got to the point where we created an asymmetric from the original symmetric signal:

hét1

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