Window comparator

A circuit comprising:

• a differential circuit stage comprising first and second unbalanced differential amplifier each connected to a reference voltage and having an input port for receiving an input voltage, the differential circuit stage producing a pair of first and second differential currents from the input voltage and the reference voltage, the differential currents varying depending on the input voltage and forming a maximum and a minimum when the input voltage is a predetermined voltage;
• a current control stage for producing a reference current and a current corresponding to a selected one of the first and second differential currents such that a voltage range is determined around the predetermined voltage which range is varied depending on whether the current is greater than the reference current;
• and
• an output stage for producing an output voltage based on the reference current and the current, the output voltage changing in level depending on whether the input voltage falls into the voltage range.

A method for forming a window of a window comparator comprising first and second unbalanced differential amplifiers, comprising the steps of:

• producing a first current from an input voltage and a reference voltage, the first current varying depending on the input voltage such that the first current has one of a maximum and a minimum when the input voltage is a predetermined voltage;
• producing a reference current and a second current corresponding to the first current such that the second current is partially greater or smaller than the reference current;
• and
• forming the window based on the second current and the reference current such that the window is determined around the predetermined voltage depending on whether the second current is greater than the reference current.