Apparatuses and methods for comparing redundant signals in functional safe systems

A method for comparing a first signal and a second signal, the method comprising:

• providing, by a first sensor element, a first measurement signal of a physical quantity via a first signal path having a first signal propagation delay;
• providing, by a second sensor element, a second measurement signal of the physical quantity via a second signal path having a second signal propagation delay different from the first signal propagation delay;
• compensating for a difference between the first signal propagation delay and the second signal propagation delay to generate a delay-compensated first measurement signal and a second delay-compensated measurement signal, including:
• generating, by a delay compensation circuit, a first trigger pulse at a first trigger time,
• generating, by the delay compensation circuit, a second trigger pulse at a second trigger time,
• in response to receiving the first trigger pulse, start acquiring, by a first sample acquisition circuit, a first plurality of samples of the first measurement signal, the delay-compensated first measurement signal being made up of the first plurality of samples;
• and
• in response to receiving the second trigger pulse, start acquiring, by a second sample acquisition circuit, a second plurality of samples of the second measurement signal, the delay-compensated second measurement signal being made up of the second plurality of samples,
• wherein the first trigger time and the second trigger time occur at different times such that an initial measurement sample of the first plurality of samples and an initial measurement sample of the second plurality of samples have a same effective sampling time;
• and
• comparing, by a comparison circuit, the delay-compensated first measurement signal and the delay-compensated second measurement signal.

An apparatus for comparing a first signal and a second signal, the apparatus comprising:

• a first signal path for a first measurement signal of a physical quantity, wherein the first signal path comprises a first sensor element configured to transform the physical quantity into the first measurement signal, and wherein the first signal path has a first signal propagation delay;
• a second signal path for a second measurement signal of the physical quantity, wherein the second signal path comprises a second sensor element configured to transform the physical quantity into the second measurement signal, the first sensor element and the second sensor element being different sensor elements, and wherein the second signal path has a second signal propagation delay different from the first signal propagation delay,
• wherein the first sensor element or one or more first circuit components of the first signal path cause the first signal propagation delay, and
• wherein the second sensor element or one or more second circuit components of the second signal path cause the second signal propagation delay;
• a delay compensation circuit configured to compensate for a difference between the first and the second signal propagation delays to generate a delay-compensated first measurement signal corresponding to the first measurement signal and a delay-compensated second measurement signal corresponding to the second measurement signal,
• wherein the delay compensation circuit is configured to trigger a first sample acquisition of the first signal path and a second sample acquisition of the second signal path at different time instances to obtain the delay-compensated first measurement signal and the delay-compensated second measurement signal at respective outputs of the first signal path and the second signal path;
• and
• comparison circuitry configured to compare the delay-compensated first measurement signal and the delay-compensated second measurement signal.