Patent ID: 6366136
Filing Date: 2002-04-02
Classification: H03K,H04N

Abstract:
An apparatus including a voltage comparator circuit with hysteresis, said voltage comparator circuit comprising:first and second power terminals for conveying a power supply voltage; an input signal terminal for conveying an input signal; a first voltage divider circuit, coupled between said input signal terminal and said first and second power terminals, that provides a first bias voltage at said input signal terminal in response to reception of said power supply voltage, wherein said input signal has opposing peak signal levels of opposite polarities relative to said bias voltage; a second voltage divider circuit, coupled between said first and second power terminals, that conducts a voltage divider current and thereby provides a second bias voltage in response to reception of said power supply voltage, wherein said first and second bias voltages are unequal; an amplifier circuit, coupled between said first and second power terminals, said input signal terminal and said second voltage divider circuit, which includes first and second circuit branches that alternately conduct first and second branch currents, respectively, wherein said first amplifier circuit branch conducts said first branch current when a sum of said first bias voltage and said input signal has a first polarity and magnitude relative to said second bias voltage, and said second amplifier circuit branch conducts said second branch current when said sum of said first bias voltage and said input signal has a second polarity and magnitude relative to said second bias voltage; and a current mirror circuit, coupled between said amplifier circuit, said second voltage divider circuit and one of said first and second power terminals, which includes an input circuit branch, coupled to said second amplifier circuit branch, that conducts said second branch current upon reception thereof, and an output circuit branch, coupled to said second voltage divider circuit, that conducts a portion of said voltage divider current in response to conduction of said second branch current by said input circuit branch, thereby causing said second bias voltage to have a first value when said first amplifier circuit branch conducts said first branch current, and said second bias voltage to have a second value when said second amplifier circuit branch conducts said second branch current.