Other Parts Discussed in Thread: TINA-TI
Hi Sirs,
Do we have INA301 analog Vout's delay time or phase-shift specifications similar to the example chart below?
Thank you and Best regards,
Wayne Chen
10/05/2018
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Hi Wayne,
We don’t have such a plot.
But it can be relatively easily derived from the bandwidth spec, or gain plot. The phase shift is 45 degrees at the dominant pole, and INA301 bandwidth is ~500KHz. One decade below the dominant pole, the phase shift is 0 degrees. Therefore if the input signal is 50KHz or lower, I don’t expect to see any phase shift. Between 50KHz and 500KHz, we can use linear interpolation (frequency on log scale) to estimate the phase shift to the first order.
Regard, Guang
Hi Guang,
Thank you for your concern. I have another two questions need your elaborate:
1. Can we say that there is no phase shift concern between DC and 50kHz?
2. Can we explain the delay time to customers in terms of slew rate?
The slew rate formula where the slew rate is 2*pi*f*V where f is the maximum frequency and V is the voltage of the waveform. As an example, take the scenario where an INA301 can amplify a signal with a peak amplitude of 3.3 volts at a frequency of 192.5kHz (2*pi*192.5k*3.3 ~= 4MV/s = 4V/us) with delay issue?
Thank you and Best regards,
Wayne Chen
10/07/2018
Hi Wayne,
Yes phase shift is 0 at and below 50KHz.
And yes that is how SR is calculated. Although this only tells you that the sinusoidal waveform is preserved with little or no distortion. To get time delay you’ll want to go back to the method I posted in my first previous post for a first order estimate. Since 192KHz falls about in the middle between 50KHz and 500KHz, the phase shift is about 22.5 degrees, which corresponds to about 3uS delay time.
Regard, Guang
Hi Kai,
Like I said, the calculation is to the first order. From simulation it is about 7 degrees at 50KHz. For all practical purposes, I think we can regard this as 0 phase shift.
Regard, Guang
Hi Kai,
You are right, they are indeed different. The online model is wrong then, it shows the bandwidth to be only 150KHz. Thanks for bring this up; we need to have it corrected.
Regard, Guang
Hi Kai and Guang,
Thank you for your concern. Would you pls elaborate the way to achieve 3us delay from 22.5deg phase shift?
Thank you and Best regards,
Wayne Chen
10/09/2018
Hi Wayne,
It should be 0.3uS, not 3uS, which corresponds to pi/8 phase shift at ~200KHz.
Regard, Guang