Offset Correction in Dual-Chopper Read-Out Circuits for Half-Bridge Capacitive Accelerometers

Konferenz: PRIME 2012 - 8th Conference on Ph.D. Research in Microelectronics & Electronics
12.06.2012-15.06.2012 in Aachen, Germany

Tagungsband: PRIME 2012

Seiten: 4Sprache: EnglischTyp: PDF

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Bergert, Jonas; Strache, Sebastian; Wunderlich, Ralf; Heinen, Stefan (Chair of Integrated Analog Circuits & RF Systems, RWTH Aachen University, 52062 Aachen, Germany)
Droste, Dirk (Robert Bosch GmbH, 72703 Reutlingen, Germany)

Sensor read-out circuits using half-bridge capacitive accelerometers suffer from a signal offset due to production mismatches. This paper describes a two-part solution to reduce the offset within the circuit to a minimum. A capacitor array is used to apply a coarse signal correction by placing digitally controlled capacitors in parallel to the sensor capacitors. The second part consists of a current DAC placed within a differential amplifier to balance out unsymmetric currents caused by the signal offset. A binary search algorithm is applied to determine the optimal configuration of both parts. The offset correction method was implemented to a dual-chopper read-out circuit and reduces the sensor offset to under 0.04 %.