Dear sir,
am testing TPA3116D2, in Gain 32dB master mode but it gives noise while the input jack is in air. what will be the reason. please suggest me.
input coupling capacitor Ci=5.6uF non polarity capacitor.
thanks
kiran
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Dear sir,
am testing TPA3116D2, in Gain 32dB master mode but it gives noise while the input jack is in air. what will be the reason. please suggest me.
input coupling capacitor Ci=5.6uF non polarity capacitor.
thanks
kiran
Hi,
in reference design manual, they are ignore the input resistance Riin series with Ci, i designed accordingly. is this Ri resistor will reduce the noise, when there is no signal present.
thanks
kiran
Hi, Kiran
Yes, changing the input resistance to smaller, the resistor thermal noise will decrease,
Compare to the Gain=26dB with input impedance=30kohm, Gain=32dB with input impedance=15kohm, the resistor thermal noise (input noise) will improve 3dB. But the Gain increased 6dB, so the output noise will increase 3dB.
I suggest you use the differential input, so it is easier for customer to layout and avoid the input noise. Or customer use the single ended input, but be careful to make sure there is no differential noise which comes from GND. Shown as below: