Circuit for sensing an analog signal, corresponding electronic system and method

A micro-electro-mechanical (MEM) system comprising:

• a MEM actuator;
• a piezoresistive sensor configured to sense mechanical information of the MEM actuator and produce an input analog signal based on the mechanical information of the MEM actuator;
• and
• a sensing circuit comprising:
• a conditioning circuit configured to receive, at an input port, the input analog signal, and to generate, at an output port, a conditioned analog signal;
• an analog-to-digital converter (ADC) coupled to the output port of the conditioning circuit, the ADC configured to receive the conditioned analog signal and provide, at a converter output node, a converted digital signal based on the conditioned analog signal, the converted digital signal being indicative of the input analog signal;
• a signal generator circuit configured to superimpose a periodic signal to the input analog signal;
• and
• a feedback circuit coupled between the output port of the conditioning circuit and a control input of the conditioning circuit, wherein the feedback circuit is configured to act on the conditioning circuit to counter variations of the periodic signal.

A method comprising:

• generating, with a sensor, an input analog signal at a first frequency;
• superimposing a periodic signal at a second frequency to the input analog signal to generate a combined analog signal, wherein the second frequency is higher than the first frequency;
• generating, using a conditioning circuit, a conditioned analog signal based on the combined analog signal;
• selectively detecting the periodic signal from the conditioned analog signal;
• and
• acting on the conditioning circuit to counter variations of the periodic signal detected from the conditioned analog signal.