Patent ID: 7202708

Claim:
A comparator having a sample mode end a latching mode, a first comparator input, a second comparator input, and an output, the comparator comprising: a cross-coupled regenerative latch for regenerating, during a latching mode, a difference signal indicative of a difference between the first comparator input and the second comparator input, said cross-coupled regenerative latch comprising: a first and a second resistor, a first and a second resonant tunneling diode, wherein the first tunneling diode is coupled in series with the first resistor to form a first resistor-diode pair, and the second tunneling diode is coupled in series with the second resistor to form a second resistor-diode pair, and a first end a second transistor, wherein a collector of the first transistor and a base of the second transistor are connected to a first terminal of the first resistor-diode pair, a collector of the second transistor and a base of the first transistor are connected to a first terminal of the second resistor-diode pair, and an emitter of the first transistor is connected to an emitter of the second transistor; a third transistor coupled to the second terminal of the first resistor-diode pair; a fourth transistor coupled to the second terminal of the second resistor-diode pair; and a current switch circuit for switching the comparator between the sample mode and the latching mode; wherein the third and the fourth transistors couple the difference signal into the latch during the sample mode and are operable as a cascode amplifier to couple a latch state to the output during the latching mode.