High-speed comparator systems and methods with enhanced noise rejection
AssigneeAnalog Devices, Inc.
InventorMichael Clarence Hopkins
Life of this patent
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Abstract
Comparator systems and methods are provided that isolate their input and output processes from each other. Comparator signals are converted to a differential current in an input process and are carried via the differential current to an output process which converts the differential current to a comparator output signal. Supply rails that are coupled to the input process are isolated from the output process and supply rails that are coupled to the output process are isolated from the input process. The differential-current transmission and supply rail isolation effectively reduce feedback and, in addition, the differential current enhances common-mode signal rejection.
Claims22
An enhanced noise-rejection comparator system that generates an output signal whose state corresponds to the polarity of a differential input signal, comprising:
- a comparator that generates a comparator signal in response to said differential input signal;
- an output buffer that generates said output signal in response to a buffer input signal;
- a current coupler that has first and second coupler portions wherein said first coupler portion generates a differential current that corresponds to said comparator signal and said second coupler portion generates said buffer input signal in response to said differential current;
- a first supply rail structure that is coupled to deliver a first supply voltage to said first coupler portion and that is isolated from said second coupler portion;
- and
- a second supply rail structure that is coupled to deliver a second supply voltage to said second coupler portion and that is isolated from said first coupler portion.
An enhanced noise-rejection comparator system that generates an output signal whose state corresponds to the polarity of a differential input signal, comprising:
- a comparator that generates a comparator voltage in response to said differential input signal;
- a voltage-to-current converter that converts said comparator voltage into a differential current;
- a current amplifier that amplifies said differential current into an amplified differential current;
- a current-to-voltage converter that converts said amplified differential current into a converter voltage;
- a buffer that generates said output signal in response to said converter voltage;
- a first supply rail structure coupled to deliver a first supply voltage to said voltage-to-current converter and isolated from said current amplifier;
- and
- a second supply rail structure coupled to deliver a second supply voltage to said current amplifier and isolated from said voltage-to-current converter.
A method of rejecting noise in the generation of an output signal whose state corresponds to the relative polarities of first and second portions of a differential input signal, comprising the steps of:
- comparing said first and second portions to form an initial output signal;
- converting said initial output signal to a differential current;
- forming said output signal in response to said differential current;
- isolating said forming step from a first supply voltage that is employed in the realization of said converting step;
- and
- isolating said converting step from a second supply voltage that is used in the realization of said forming step;
- said differential current and said isolating steps enhancing noise rejection.
Dependencies are inferred from the claim text.