DIRECT COUPLING OF A CAPACITIVE SENSOR TO A DELTA-SIGMA CONVERTER

摘要

Embodiments of an apparatus for direct coupling of a capacitive sensor to a delta-sigma converter are described. One apparatus includes a sensor, a charge coupling circuit configured to transfer at least a portion of charge generated by the sensor to an integrating circuit, a first charge feedback circuit configured to feed back charge to the sensor, a second charge feedback circuit configured to feed back charge to the integrating circuit, a comparing circuit configured to detect accumulated charge at the integrating circuit for a current cycle to determine a polarity of charge feedback for a subsequent cycle, and a logic circuit configured to provide a digital output corresponding to the sensed quantity and also configured to provide the polarity of charge feedback determined by the comparing circuit to the first charge feedback circuit and also to the second charge feedback circuit.

主权项

1. An apparatus, comprising:
a sensor configured to generate charge in proportion to a sensed quantity; a charge coupling circuit configured to transfer at least a portion of the charge generated by the sensor to an integrating circuit; a first charge feedback circuit configured to feed back charge to the sensor; a second charge feedback circuit configured to feed back charge to the integrating circuit, the integrating circuit being configured to accumulate charge in proportion to a difference between the charge transferred from the sensor to the integrating circuit by the charge coupling circuit and the charge fed back to the integrating circuit by the second charge feedback circuit; a comparing circuit configured to detect accumulated charge at the integrating circuit for a current cycle to determine a polarity of charge feedback for a subsequent cycle; and a logic circuit configured to provide at least one of a digital output corresponding to the sensed quantity and the polarity of charge feedback determined by the comparing circuit to the first charge feedback circuit for controlling the charge fed back to the sensor and also to the second charge feedback circuit for controlling the charge fed back to the integrating circuit.