ADxRS614: Gyro Null fluctuates

Q 

I am using ADXRS614 gyroscope in one of my projects. I am having trouble with
this sensor and I couldn't find solution for it. The problem is gyro's outputs
swing +-5mV. So adc output changes in stall position at least +-4 Lsb because
of this i can't hold angle position or any other values correctly. Adc and
gyro's Vrefs connected to same source so I eliminated some of errors by using
ratiometric system. Gyro connected as described in pdf and using about 30Hz
Bandwith. Do you have any suggestions to suppress this DC output swing.

 

A 

The ultimate drift accuracy that you can achieve by calibrating a gyro depends
on several factors

- precision in the measurement of null and sensitivity (e.g. due to noise,
measurement resolution)

- precision/repeatability in the measurement of temperature of the IC.

- non-linearity of the offset vs. temperature and sensitivity vs. temperature
characteristics (how many temperature points are calibrated)

As mentioned in the datasheet using a 3-point calibration technique, it is
possible to calibrate the null and sensitivity drift of the ADXRS614 to an
overall accuracy of nearly 200°/hour. An overall accuracy of 40°/hour or better
is possible using more points. Limiting the bandwidth of the device reduces the
flat-band noise during the calibration process, improving the measurement
accuracy at each calibration point.