Are you sure it is a DC shift you are seeing and not an AC signal due
     to cross-sensitivity of the accelerometer.

     Michael Pedersen
     Knowles Electronics Inc.
     e-mail: [email protected]


______________________________ Reply Separator
_________________________________
Subject: DC-bias shift in the presence of strong vibration in MEMS ac
Author:  "Mike Falck"  at -FABRIK/Internet
Date:    10/26/98 7:58 AM


From: Mike Falck
Date: Mon, Oct 26, 1998 7:58 AM
Subject: DC-bias shift in the presence of strong vibration in MEMS
accelerometers. (Pedulous Rectification?)
To: MEMS
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We are observing a DC-bias shift in the presence of strong vibration in =
the non-sensitive axis of a MEMS accelerometer.  We have heard that it =
is or could be related to a phenomenon called "Pedulous Rectification".  =
We would like any information regarding this issue.

The experiment we have performed is to take a MEMS accelerometer and =
vibrate it in its non-sensitive axis from 50Hz-2KHz at 1.5g peak sine =
wave.  The DC-offset or bias will change as much as 60mV at certain =
frequencies.  The sensors we are using have a 0g bias at ~2.5V and have =
a sensitivity of 2V/g.

Since we are using the accelerometers in a precision tilt application =
the 60mV appears as a significant error.

Thanks in advance,

Mike Falck
Crossbow Technology
Ph:  (408)965-3315.
Email: [email protected]


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We are observing a DC-bias shift in =
the presence=20
of strong vibration in the non-sensitive axis of a MEMS =
accelerometer.  We=20
have heard that it is or could be related to a phenomenon called =
"Pedulous=20
Rectification".  We would like any information regarding this=20
issue.
 
The experiment we have performed is =
to take a=20
MEMS accelerometer and vibrate it in its non-sensitive axis from =
50Hz-2KHz at=20
1.5g peak sine wave.  The DC-offset or bias will change as much as =
60mV at=20
certain frequencies.  The sensors we are using have a 0g bias at =
~2.5V and=20
have a sensitivity of 2V/g.
 
Since we are using the =
accelerometers in a=20
precision tilt application the 60mV appears as a significant =
error.
 
Thanks in advance,
 
Mike Falck
 
Crossbow Technology
 
Ph:  = (408)965-3315.
Email: [email protected]
 

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From: "Mike Falck" 
Subject: DC-bias shift in the presence of strong vibration in  MEMS
accelerometers. (Pedulous Rectification?)
Date: Mon, 26 Oct 1998 07:58:58 -0800
To: [email protected]
X-URL: http://mems.isi.edu/mems.html
Reply-To: "Mike Falck" , [email protected]

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