Systems and methods for compensating the input offset voltage of a comparator

A system to compensate for an input offset voltage of a zero crossing detection circuit for a power stealing circuit, the system comprising:

• an input configured to connect to an AC power source that provides power to a load;
• a zero crossing detection circuit responsive to the input, the zero crossing detection circuit configured to determine a zero crossing of an input signal provided by the ac power source, and wherein the zero crossing detection circuit includes a comparator having an input offset voltage;
• and
• a compensation circuit responsive to the zero crossing detection circuit, wherein the compensation circuit is configured to provide a first compensation signal to an inverting input of the comparator of the zero crossing detection circuit, and a second compensation signal to a non-inverting input of the comparator of the zero crossing detection circuit, wherein the polarity of the first compensation signal is opposite to the polarity of the second compensation signal.

A system to compensate for an unwanted input offset voltage of a zero crossing detection circuit of a power stealing circuit, the system comprising:

• an input configured to connect to an AC power source that provides an AC input signal to a load;
• a zero crossing detection circuit configured to determine a zero crossing of the AC input signal at the input, the zero crossing detection circuit having an unwanted input offset voltage;
• and
• a compensation circuit for at least partially compensating for the unwanted input offset voltage of the zero crossing detection circuit, the compensation circuit configured to provide compensation to the zero crossing detection circuit based, at least in part, on a measure related to a difference between an amount of time that the AC input signal is above a reference voltage and an amount of time the input signal is below the reference voltage.

A method comprising:

• receiving an AC input signal from an AC power source that provides power to a load;
• determine a zero crossing of the AC input signal using a zero crossing detection circuit having an unwanted input offset voltage;
• identifying a measure related to a difference between an amount of time that the AC input signal is above a reference voltage and an amount of time the input signal is below the reference voltage;
• at least partially compensating for the unwanted input offset voltage of the zero crossing detection circuit based, at least in part, on the measure related to the difference between the amount of time that the AC input signal is above the reference voltage and the amount of time the input signal is below the reference voltage.