Half-bridge for capacitive sensing

Details Half-bridge for capacitive sensing Half-bridge for capacitive sensing

2011-04-12

2011-04-12

Dole, Timothy J (Department: 2858)

Electricity: measuring and testing

Impedance, admittance or other quantities representative of...

Lumped type parameters

C324S678000, C324S679000

Reexamination Certificate

active

07924029

ABSTRACT:
Methods and apparatus are provided for measuring a ratio of capacitances. The apparatus include a comparator including a comparator input, a comparator output, and a reference voltage; a first capacitive element including a first capacitance, a first electrode coupled to the comparator input, and a second electrode; a first biasing element coupled to the first electrode; a digitally-controlled voltage waveform generator for generating a varying waveform, the voltage waveform generator including a voltage waveform generator output coupled to the second electrode; a second capacitive element including a second capacitance and a third electrode coupled to the comparator input; and a controller coupled to the comparator output, the controller configured to control the digitally-controlled voltage waveform generator, wherein an output signal of the comparator is dependent on a ratio comprising the first capacitance and the second capacitance, and the first capacitive element and/or the second capacitive element has a variable capacitance.

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