Capacitance Sensor

A capacitance sensor, comprising:

• at least one electrode;
• a frequency spread signal generation circuit coupled to the at least one electrode to apply a frequency spread signal phase-modulated according to a spread symbol sequence to the at least one electrode;
• a receiver circuit coupled to the at least one or a further electrode to receive a version of the phase-modulated frequency spread signal which depends on a capacitance applied to the at least one electrode;
• and
• an evaluation circuit which is coupled to the receiver circuit to determine a capacitance value based on the received, dependent version of the phase-modulated frequency spread signal.

A capacitance sensor, comprising:

• a plurality of electrodes;
• a frequency spread signal generation circuit which is coupled to the plurality of electrodes and which is implemented to control the plurality of electrodes in time division multiplex so that, for a controlled electrode, a frequency spread signal based on a spread symbol sequence with a spread symbol rate and a periodic signal is applied for a spread symbol duration;
• a receiver circuit coupled to the plurality of electrodes or a further electrode to receive a version of the frequency spread signal which depends on a capacitance applied to the plurality of electrodes;
• and
• an evaluation circuit coupled to the receiver circuit to determine a capacitance value based on sampling values of the received dependent version of the frequency spread signal which are determined by a sampling rate which is equal to or higher than the spread symbol rate.

A capacitance sensor, comprising:

• at least one electrode;
• means for applying a frequency spread signal to the at least one electrode, wherein the frequency spread signal is based on a spread sequence and a periodic signal with a frequency;
• means for varying the frequency of the periodic signal;
• means for receiving a version of the frequency spread signal which depends on a capacitance applied to the at least one electrode;
• and
• means for determining a capacitance value or a signal that may be derived from the capacitance value based on the received dependent version of the frequency spread signal.

A capacitance sensor, comprising:

• at least one electrode, wherein a capacitance may be measured between the at least one electrode and a further electrode or a reference potential;
• a circuit implemented to apply a periodic signal with a variable frequency to the at least one electrode and comprising a spread sequence generation circuit to change the periodic signal depending on a spread sequence generated by the spread sequence generation circuit;
• a circuit implemented to detect a signal dependent on the capacitance and the periodic signal at the at least one or the further electrode, wherein the circuit is coupled to the spread sequence generation circuit so that detection depends on the spread sequence;
• and
• an evaluation circuit coupled to the circuit for detecting to determine a sensor output signal dependent on the capacitance from the dependent signal.

A method for detecting a capacitance or a capacitance change, comprising:

• applying a frequency spread signal to at least one electrode, wherein the frequency spread signal is based on a spread sequence and a periodic signal with a frequency;
• varying the frequency of the periodic signal;
• receiving a version of the frequency spread signal which depends on a capacitance applied to the at least one electrode;
• and
• determining the capacitance or a value which may be derived from the capacitance from the received dependent version of the frequency spread signal.

A computer program for performing a method for detecting a capacitance or a capacitance change, comprising:

• applying a frequency spread signal to at least one electrode, wherein the frequency spread signal is based on a spread sequence and a periodic signal with a frequency;
• varying the frequency of the periodic signal;
• receiving a version of the frequency spread signal which depends on a capacitance applied to the at least one electrode;
• and
• determining the capacitance or a value which may be derived from the capacitance from the received dependent version of the frequency spread signal,
• when the computer program is executed on a computer and/or microcontroller.