CMOS low-voltage comparator
First Claim
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1. A comparator circuit comprising:
- a differential input circuit that receives first and second analog input signal transitions for comparison with a reference voltage,an output circuit that receives charging and discharging current in response to said first and second input signal transitions, respectively;
a first delay path comprising a first plurality of current mirrors coupled to said input circuit and said output circuit that facilitates application of said charging current to said output in response to said first signal transition; and
a second delay path coupled to said input circuit and said output circuit that facilitates application of said discharging current to said output circuit in response to said second signal transition, wherein said first and second delay paths operate in approximately the same amount of time.
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Abstract
A comparator circuit providing for improved symmetry of operation. The circuit includes two delay paths to facilitate rising and falling input transitions. Such paths are made up of an equal number and type of current mirrors. The circuit also includes an input differential pair wherein both delay paths are coupled to a single transistor of the pair.
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Citations
19 Claims
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1. A comparator circuit comprising:
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a differential input circuit that receives first and second analog input signal transitions for comparison with a reference voltage, an output circuit that receives charging and discharging current in response to said first and second input signal transitions, respectively; a first delay path comprising a first plurality of current mirrors coupled to said input circuit and said output circuit that facilitates application of said charging current to said output in response to said first signal transition; and a second delay path coupled to said input circuit and said output circuit that facilitates application of said discharging current to said output circuit in response to said second signal transition, wherein said first and second delay paths operate in approximately the same amount of time. - View Dependent Claims (2, 3, 4, 5)
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6. A comparator circuit comprising:
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a first input transistor coupled to a non-oscillating signal input and a second input transistor coupled to an analog signal; a first current mirror coupled to said first input transistor and producing a first mirrored current IM1; a second current mirror coupled to said first input transistor and producing a second mirrored current IM2, said second mirrored current representing a portion of a predetermined current value IMAX; and an output stage containing a current-sourcing transistor and a current-sinking transistor for producing a digital output, wherein said current-source transistor sources current approximately equal to IM1 and said current-sinking transistor sinks current approximately equal to IMAX-IMA. - View Dependent Claims (7, 8, 9)
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10. A comparator circuit comprising:
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an input differential pair containing a first transistor and a second transistor; a first input path coupled to said first transistor, said first input path receiving an oscillating input signal; a second input path coupled to said second transistor, said second input path receiving a non-oscillating input signal; a first delay path coupled to said second transistor that conveys a charging current; a second delay path coupled to said second transistor that conveys a discharging current; and an output coupled to said first and second delay paths. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification