Receiver circuit, corresponding system and method

A method, comprising:

• receiving a modulated signal over a radiofrequency (RF) carrier;
• removing said RF carrier with an envelope detector;
• producing a replica of the modulated signal having the RF carrier removed therefrom between first and second output nodes of a differential stage having a first input coupled to the envelope detector and a second input configured to receive a reference signal;
• producing, via a comparator coupled to the first and second output nodes of the differential stage, a PWM-modulated signal having on and off times based on said replica of the modulated signal having the RF carrier removed therefrom;
• actuating a first switch to short-circuit the input to the envelope detector;
• actuating a second switch to feed back to a storage capacitor coupled to the second input of the differential stage a signal indicative of the difference between the first output node and the second output node of the differential stage;
• actuating a third switch to short-circuit the input to the comparator;
• and
• activate a sequence of offset compensation phases comprising:
• a start-up phase and at least one standby phase where the first switch, the second switch and the third switch are actuated in the absence of the PWM-modulated signal;
• and
• a working phase alternating with the start-up phase or the at least one standby phase in the presence of the PWM-modulated signal wherein the first switch, the second switch and the third switch are actuated during off times of the PWM-modulated signal.

A circuit, comprising:

• an envelope detector having a first input, a second input and an output;
• a first differential amplifier having a first input coupled to the output of the envelope detector, a second input coupled to receive a reference voltage, a first output and a second output;
• a second differential amplifier having a first input coupled to the first output of the first differential amplifier, a second input coupled to the second output of the first differential amplifier, and an output;
• a comparator having a first input coupled to the first output of the first differential amplifier, a second input coupled to the second output of the first differential amplifier, and an output from which a pulse width modulation (PWM) signal having on and off times is generated;
• and
• offset compensation circuitry comprising:
• a first switch configured to selectively short the first input and second input of the envelope detector;
• a second switch configured to selectively connect the output of the second differential amplifier to the second input of the first differential amplifier;
• and
• a third switch configured to selectively ground the output of the comparator.