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# ADXRS652 Power Supply Design and Noise Density

We use ADXRS652 in our new products and noticed the Rate Noise Density of this gyro is 0.06°/s/√Hz,  does it means if the bandwidth is 2500Hz, the noise is 0.06*√2500=3°/s?

We are going to use a 16bit A/D to convert gyro's output to digital, the resolution should be 0.0127°/s, if the gyro's bandwidth is 2.5KHz, the noise is 3°/s and greater than A/D resolutioin, in that case, seems a 10bit A/D is enough, am I right?

Since the noise density is 0.06°/s/√Hz, a 16bit A/D will enough to whole bandwidth application, is it correct?

Anohter quesition is about the power supply of the ADXRS652, there is 3 power supply pins, Vdd, AVcc and Vratio, based on my understanding, all  power supply pins can be connect to a single supply if high precision is not needed. If high precision is needed,  3 power supplys used to Vdd, AVcc and Vratio separately may be is the best option, but 3 power supply may cost more.

In our case (high precision and high bandwidth needed), we are going to use a LDO (1% precision) for the Vdd, use a high precision 5V reference for the Vratio, but what should we do about the AVcc? If we use LDO to power supply AVcc, may be the precision in not enough, but if we use the 5V reference to the AVcc, may be the 5V reference supply current is not enough cause 3 gyro used on one pcb board.

Is there any applicaion notes about ADXRS652 power supply design or spcefictaion of the AVcc operating current and precision?

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Anohter quesition is about the power supply of the ADXRS652, there is 3 power supply pins, Vdd, AVcc and Vratio, based on my understanding, all  power supply pins can be connect to a single supply if high precision is not needed. If high precision is needed,  3 power supplys used to Vdd, AVcc and Vratio separately may be is the best option, but 3 power supply may cost more.

The key insight I can offer on Vratio, is that intends to be the supply that supported the entire signal chain (amp, filter, adc), so that you can manage the signal range, along with the scale variation, with respect to supply.  In designs that I am aware of, the other two supplies can be tied together, with good, local decoupling.