Patent ID: 7352221

Claim:
A hysteretic amplifier comprising: a first differential pair of first and second transistors receiving first and second input voltages and generating a first output voltage; third and fourth transistors coupled to the first and second transistors, respectively, and coupled to receive first and second control signals, respectively; a multiplexer that generates the first and the second control signals in response to a hysteretic select signal; a first resistor coupled to a drain of the first transistor; a second resistor coupled to a drain of the second transistor; a third resistor coupled to a drain of the third transistor; and a fourth resistor coupled to a drain of the fourth transistor, wherein the multiplexer causes the hysteretic amplifier to have a positive hysteresis when the hysteretic select signal is in a first state, and the multiplexer causes the hysteretic amplifier to have a negative hysteresis when the hysteretic select signal is in a second state.