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Want to know the GBWP of TDA7396 (45W/2W BRIDGE CAR RADIO AMPLIFIER).
I do know that it is just a car amplifier but I do need to know the GBWP for it please, unfortunetely the datasheet of the chip was not helpful for finding GBWP.
An amplifier like that doesn't really have a Gain Bandwidth Product. The GBWP is typically quoted for an op-amp so that the maximum frequency for a particular gain can be estimated. On the TDA7396 the gain is fixed at 20 times.
The roll-off frequency is 75 kHz, where the gain starts to fall, so you could estimate the GBWP at 20 x 75 kHz = 1.5 MHz. However, the roll-off might well be faster than the 3 dB/octave that is implied by having a GBWP. Also, you can't really change the feedback ratio, to sacrifice gain for frequency, so GBWP is fairly meaningless.
Does The roll-off frequency of 75kHz means just a 3dB fall for the gain at that freq? If so then the gain of 20 times is considered for just audio frequncies (20Hz to 20Khz), right?
Ok so justplease tell me if that chip is able to work at 60kHz for instance, like it does at audio frequncies? is the gain remain constant at 60kHz too. My guess is that it does because 60kHz is < 75kHz so we did not reached to the rollof freq ie 75kHz, right? But if the gain is fixed at 20, then we should have the gain of 20 at 60kHz too, right? confused!
Firstly, 60 kHz is less than 75 kHz, and that is shown as 60 kHz < 75 kHz.
The minimum roll-off frequency is quoted as being 75 kHz, at -3 dB. That means that for a fixed input level, the output power will fall to half as the signal frequency increases to some frequency beyond 75 kHz. Although it doesn't say how consistent the output level is, I strongly suspect that the gain will be nearly flat until the gain rolls off at high frequency.
I would a expect to see a small reduction in gain starting at about 50 kHz, because the gain can be a lot less, about 14, by 75 kHz.
The output of a single-pole lowpass filter (in an opamp or in an audio amp) causes the output to drop 6dB (half the voltage) per octave, not 3dB per octave.
Its minimum rolloff is -3dB at 75kHz so its output will be reduced a little at 15kHz.
The output of a single-pole lowpass filter (in an opamp or in an audio amp) causes the output to drop 6dB (half the voltage) per octave, not 3dB per octave.
Its minimum rolloff is -3dB at 75kHz so its output will be reduced a little at 15kHz.
As we all know the bandwidth is a freq where the volatge gain of an amplifier reaches to 0.707 of its max (i.e -3dB of reduction in voltage gain). so the bandwidth is where the volatge gain drops by 3dB
the GBWP for LM357 is 10MHz.
the formula for caculating the bandwidth says"
Gain x bandwidth = GBWP
Know suppse that the voltage gain of an op-amp is 5.6 (i.e 15dB), so the bandwidth would be:
10MHz/5.6 = 1.8MHz of bandwidth.
so the question is:
Can we tell that at 1.8MHz (which is the bandwidth of LF357 by the gain of 5.6)the voltage gain drops by 3dB and reaches to 12db or to 3.96?
As we all know the bandwidth is a freq where the volatge gain of an amplifier reaches to 0.707 of its max (i.e -3dB of reduction in voltage gain). so the bandwidth is where the volatge gain drops by 3dB
the GBWP for LM357 is 10MHz.
the formula for caculating the bandwidth says"
Gain x bandwidth = GBWP
Know suppse that the voltage gain of an op-amp is 5.6 (i.e 15dB), so the bandwidth would be:
10MHz/5.6 = 1.8MHz of bandwidth.
so the question is:
Can we tell that at 1.8MHz (which is the bandwidth of LF357 by the gain of 5.6)the voltage gain drops by 3dB and reaches to 12db or to 3.96?
There is no LM357. Maybe you mean the LF357? Its GBP is 20MHz, not 10MHz.
The gain at 1.8MHz is 20 on the graph on its datasheet but it shows a GBP of 28MHz.
There is no LM357. Maybe you mean the LF357? Its GBP is 20MHz, not 10MHz.
The gain at 1.8MHz is 20 on the graph on its datasheet but it shows a GBP of 28MHz.
Oh typo! Yea I meant LF357. I do not matter if your datasheet tells GBWP of 20MHz, mine tells 10MHz. But am I right about what I told at my above post? Or I am just confusing myself?
I just want to know if this is true or I am wrong?:
the GBWP for LM357 is 10MHz.
the formula for caculating the bandwidth says"
Gain x bandwidth = GBWP
Know suppse that the voltage gain of an op-amp is 5.6 (i.e 15dB), so the bandwidth would be:
10MHz/5.6 = 1.8MHz of bandwidth.
so the question is:
Can we tell that at 1.8MHz (which is the bandwidth of LF357 by the gain of 5.6)the voltage gain drops by 3dB and reaches to 12db or to 3.96?
I came across a new problem regarding Slew Rate. What about when the input signal is Square wave and not Sine? Is SR important at this sitution? If so what to do?
A low slew rate causes a sine-wave or a square-wave to become a triangle wave. As the frequency is increased the output cannot slew fast enough to keep up so the output amplitude gets smaller.
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