Peak voltage detector and related method of generating an envelope voltage

A method, comprising:

• receiving an oscillating voltage at an input terminal;
• rectifying the oscillating voltage with a rectifier producing a rectified voltage at an output of the rectifier;
• charging a first integrated capacitor to an envelope voltage representing a detected peak value of the oscillating voltage, by closing a first switch positioned between the output of the rectifier and the integrated capacitor;
• storing the envelope voltage on the capacitor by opening the first switch;
• charging an auxiliary integrated capacitor to an auxiliary voltage representing a last detected peak value of the oscillating voltage, by closing a second switch positioned between the output of the rectifier and the auxiliary integrated capacitor;
• storing the auxiliary voltage on the auxiliary integrated capacitor by opening the second switch;
• comparing the stored auxiliary voltage on said auxiliary integrated capacitor with the oscillating voltage and generating a first command signal if a difference between the auxiliary voltage and the oscillating voltage is smaller than a selected offset voltage;
• measuring a time elapsed from a most recent active switching edge of said first command signal;
• closing said second switch when said first command signal is active or when a pre-established time interval has elapsed from a most recent active switching edge of said first command signal, and opening said second switch otherwise;
• forcing low an auxiliary command signal after a predefined time interval has elapsed from a last edge of said first command signal;
• masking any eventual switching of said first command signal during a pre-established time interval starting from last forcing low of the auxiliary command signal;
• enabling a tracking circuit of the oscillating voltage for forcing, for a time interval, said oscillating voltage on the auxiliary integrated capacitor, when said pre-established time interval has elapsed from the most recent active switching edge of said first command signal;
• closing said first switch when said first command signal is active and, at the same time, said auxiliary command signal is logically high, or when a pre-established time interval has elapsed from the most recent active switching edge of said first command signal and, at the same time, said auxiliary command signal is logically high, and opening said first switch otherwise;
• closing said second switch when said first command signal is logically active or when a pre-established time interval has elapsed from the most recent active switching edge of said first command signal, and opening said second switch otherwise.

A device, comprising:

• a peak detector circuit having:
• a rectifying circuit, having an input and an output, configured to generate an rectified voltage at the output corresponding to an oscillating voltage at the input;
• a first capacitor;
• an auxiliary capacitor;
• a comparator having a first input coupled to a terminal of the auxiliary capacitor and a second input coupled to an input of the peak detector, and configured to produce a first command signal at an output of the comparator if the oscillating voltage exceeds a voltage corresponding to a voltage stored on the auxiliary capacitor;
• a first switch positioned between the terminal of the auxiliary capacitor and the output of the rectifying circuit and configured to couple the auxiliary capacitor to the output of the rectifying circuit when closed, and to isolate the auxiliary capacitor from the output of the rectifying circuit when open, the first switch being configured to close when the first command signal is present at the output of the comparator;
• a logic circuit configured to force low an auxiliary command signal after a predefined time interval has elapsed from a most recent active switching edge of said first command signal;
• masking any eventual switching of said first command signal during a pre-established time interval starting from a most recent forcing low of the auxiliary command signal;
• and
• a second switch positioned between a terminal of the first capacitor and the output of the rectifying circuit and configured to couple the first capacitor to the output of the rectifying circuit when closed, and to isolate the first capacitor from the output of the rectifying circuit when open, the second switch being configured to close when said first command signal is active and, at the same time, said auxiliary command signal is logically high, or when a pre-established time interval has elapsed from the most recent active switching edge of said first command signal and, at the same time, said auxiliary command signal is logically high, and opening said second switch otherwise.