Patent ID: 9529029
Filing Date: 2016-12-27
CPC Classification: G01R,H03K

Claim Text:
1. A capacitive detection system, comprising: a first AC signal generator configured to generate a first AC voltage signal, a second AC signal generator configured to generate a second AC voltage signal, said second AC voltage having a lower frequency than said first AC signal, a first mixer for mixing said first AC voltage signal and said second AC voltage signal and for generating a modulated AC voltage signal, a control and evaluation unit operatively coupled to an antenna electrode or a separate receiving electrode, said control and evaluation unit comprising a current measurement circuit configured to measure current signals, said current signals comprising amplitude and/or phase of a current flowing in said antenna electrode or in said separate receiving electrode, said control and evaluation unit being configured to determine a capacitance to be measured based upon said measured current signals, and to output an output signal indicative of said determined capacitance; wherein said current measurement circuit comprises a capacitance to current or voltage converter coupled across said capacitance to be determined, said capacitance to current or voltage converter comprising an input and an output, and a second mixer operatively coupled to the output of said capacitance to current or voltage converter, and wherein said first mixer is operatively coupled to said capacitance to current or voltage converter for supplying said modulated AC voltage signal to said input of said capacitance to current or voltage converter and wherein said first AC signal generator is operatively coupled to a second input of said second mixer.