Method for testing an analog-to-digital converter unit having delta-sigma modulation

A method for testing an analog-to-digital converter unit, which is configured to convert an analog input signal into a digital output signal using delta-sigma modulation, the method comprising:

• generating an analog input signal;
• applying a predefined interference signal to the analog input signal and storing a resulting digital output signal as a test result;
• and
• determining that a fault is present based on a transfer function of the analog-to-digital converter unit, which is ascertained from the test result and the input signal, having a deviation from a predefined target transfer function that is greater than a predefined reference value, a fault signal being output when a fault is determined;
• wherein after the predefined interference signal is applied, a negated predefined interference signal is applied to the analog input signal and a resulting digital output signal is stored as additional test result, a presence of the fault being determined based on a difference between the test result and additional test result being greater than a predefined reference value.

An analog-to-digital converter unit, comprising:

• a delta-sigma modulator configured to convert an analog input signal into a digital output signal using delta-sigma modulation;
• and
• a self-test module configured to perform the following:
• generating an analog input signal,
• applying a predefined interference signal to the analog input signal and store a resulting digital output signal as a test result, and
• determining that a fault is present if a transfer function of the analog-to-digital converter unit, which is ascertained from the test result and the input signal, has a deviation from a predefined target transfer function which is greater than a predefined reference value, the self-test module being configured to output a fault signal if a fault is determined;
• wherein the delta-sigma modulator has a loop filter and a quantizer, the predefined interference signal being applied via a coupling point between the loop filter and the quantizer.

An analog-to-digital converter unit, comprising:

• a delta-sigma modulator configured to convert an analog input signal into a digital output signal using delta-sigma modulation;
• and
• a self-test module configured to perform the following:
• generating an analog input signal,
• applying a predefined interference signal to the analog input signal and store a resulting digital output signal as a test result, and
• determining that a fault is present if a transfer function of the analog-to-digital converter unit, which is ascertained from the test result and the input signal, has a deviation from a predefined target transfer function which is greater than a predefined reference value, the self-test module being configured to output a fault signal if a fault is determined;
• wherein the self-test module is configured to, after the predefined interference signal has been applied, apply a negated predefined interference signal to the analog input signal and store a resulting digital output signal as an additional test result, a presence of the fault being determined if a difference between the test result and additional test result is greater than a predefined reference value.