US5386207A
Expired / Lapsed
US
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Comparator with application in data communication
Assignee: WINDBOND ELECTRONICS NORTH AMERICA Corp A CA CORP
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Filing: 1992-06-23
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Granted: 1995-01-31
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Expires: 2012-06-23
Abstract
Abstract A comparator that may be used in data communications transmission lines, in particular, an Ethernet Twisted-Pair line. The comparator accepts as input the differential voltage from the transmission lines. The comparator uses feedback circuitry to monitor particular voltages within the comparator and adjust them as necessary to mitigate the effect of bias offset within the comparator that may result from, for instance, temperature driven device parameter variations. The comparator also minimizes the effect of power supply noise. The feedback circuitry ensures that as the comparator input differential voltage approaches zero (i.e., when the comparator outputs should switch from a high voltage to a low voltage or vice versa), the input of a comparator output amplifier is situated in the middle of the high gain region of the output amplifier, ready to quickly trigger switching of the comparator output when the comparator input differential voltage crosses zero volts. In one embodiment, the feedback circuitry comprises an operational amplifier and two resistive-capacitive structures.
Inventors
- 👤 San L. Lin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:00
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45479; H03F3/45632; H03F3/45636; H03F3/45641; H03F3/4565; H03F3/45076; H03F3/45179; H03F3/45183; H03F3/45659; H03K; H03K5/00; H03K5/22; H03K5/24; H03K5/2472; H03K5/2481; H03F2203/00; H03F2203/45; H03F2203/45418; H03F2203/45424; H03F2203/45508; H03F2203/45732
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
126 words
A comparator for use with a data communications system, comprising: a first stage which accepts a differential voltage as comparator input, buffers the differential voltage, and produces first and second voltages; a voltage averaging network that averages the first and second voltages to produce a third voltage; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the first stage such that the third voltage is maintained equal to the reference voltage; and a second stage which amplifies the first voltage and produces an output voltage as comparator output; wherein the reference voltage is equal to a voltage approximately centered within a high gain region of the second stage.
Claim 2
Dependent Claim
126 words
A comparator for use with a data communications system, comprising: a first stage which accepts a differential voltage as comparator input, buffers the differential voltage, and produces first and second voltages; a voltage averaging network that averages the first and second voltages to produce a third voltage; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the first stage such that the third voltage is maintained equal to the reference voltage; and a second stage which amplifies the first voltage and produces an output voltage as comparator output; wherein the reference voltage is equal to a voltage approximately centered within a high gain region of the second stage.
Claim 3
Dependent Claim
43 words
A comparator as in claim 1 wherein the voltage averaging network comprises a resistive-capacitive network having two mutually coupled sections with parallel resistive-capacitive elements, the two network sections respectively accepting the first and second voltages and furnishing the third voltage where mutually coupled.
Claim 4
Dependent Claim
155 words
A comparator for use with a data communications system, comprising: a low gain stage which accepts a differential voltage as comparator input, buffers the differential voltage, and produces first and second voltages; a resistive-capacitive voltage averaging network that averages the first and second voltages to produce a third voltage, wherein the resistance of the resistive capacitive network is provided by a lightly doped silicon region; and the capacitance of the resistive-capacitive network is provided by the lightly doped silicon region and a polysilicon region which are separated by an insulating region; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the low gain stage such that the third voltage is maintained equal to the reference voltage; and a high gain stage which amplifies the first and second voltages voltage and produces an output voltage as comparator output.
Claim 5
Dependent Claim
155 words
A comparator for use with a data communications system, comprising: a low gain stage which accepts a differential voltage as comparator input, buffers the differential voltage, and produces first and second voltages; a resistive-capacitive voltage averaging network that averages the first and second voltages to produce a third voltage, wherein the resistance of the resistive capacitive network is provided by a lightly doped silicon region; and the capacitance of the resistive-capacitive network is provided by the lightly doped silicon region and a polysilicon region which are separated by an insulating region; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the low gain stage such that the third voltage is maintained equal to the reference voltage; and a high gain stage which amplifies the first and second voltages voltage and produces an output voltage as comparator output.
Claim 6
Dependent Claim
130 words
A comparator for use with a data communications system, comprising: a low gain stage which accepts a differential voltage as comparator input, buffers the differential voltage, and produces first and second voltages; a voltage averaging network that averages the first and second voltages to produce a third voltage; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the low gain stage such that the third voltage is maintained equal to the reference voltage; and a high grain stage which amplifies the first and second voltages and produces an output voltage as comparator output; wherein the high gain stage has a logic threshold voltage and the reference voltage equals the logic threshold voltage.
Claim 7
Dependent Claim
130 words
A comparator for use with a data communications system, comprising: a low gain stage which accepts a differential voltage as comparator input, buffers the differential voltage, and produces first and second voltages; a voltage averaging network that averages the first and second voltages to produce a third voltage; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the low gain stage such that the third voltage is maintained equal to the reference voltage; and a high grain stage which amplifies the first and second voltages and produces an output voltage as comparator output; wherein the high gain stage has a logic threshold voltage and the reference voltage equals the logic threshold voltage.
Claim 8
Dependent Claim
174 words
A comparator for data communications applications, comprising: a differential low gain amplifier stage with first and second data input terminals and first and second output terminals; a first output amplifier having an input terminal with a particular logic threshold connected to the first output terminal of said differential low gain amplifier stage; a resistive-capacitive network having first and second network input terminals respectively connected to the first and second output terminals of said differential low gain amplifier stage, said network being operative to provide an average of the voltages applied to said first and second network input terminals at a network output terminal; a voltage reference circuit having an output terminal for furnishing a voltage equal to the logic threshold of said first output amplifier; and an operational amplifier having a first input terminal connected to the output terminal of said voltage reference circuit, a second input terminal connected to said resistive-capacitive network output terminal, and an output terminal connected to said differential low gain amplifier stage so as to provide negative feedback thereto.
Claim 9
Dependent Claim
174 words
A comparator for data communications applications, comprising: a differential low gain amplifier stage with first and second data input terminals and first and second output terminals; a first output amplifier having an input terminal with a particular logic threshold connected to the first output terminal of said differential low gain amplifier stage; a resistive-capacitive network having first and second network input terminals respectively connected to the first and second output terminals of said differential low gain amplifier stage, said network being operative to provide an average of the voltages applied to said first and second network input terminals at a network output terminal; a voltage reference circuit having an output terminal for furnishing a voltage equal to the logic threshold of said first output amplifier; and an operational amplifier having a first input terminal connected to the output terminal of said voltage reference circuit, a second input terminal connected to said resistive-capacitive network output terminal, and an output terminal connected to said differential low gain amplifier stage so as to provide negative feedback thereto.
Claim 10
Dependent Claim
147 words
A comparator as in claim 5 wherein said resistive-capacitive network is a distributed network, comprising: a first lightly doped region diffused in a semiconductor substrate for providing a first resistance; a first conductive plate disposed over said first lightly doped region and insulated therefrom for providing a first capacitance; a second lightly doped region diffused in a semiconductor substrate for providing a second resistance; and a second conductive plate disposed over said first lightly doped region and insulated therefrom for providing a second capacitance; wherein said first network input terminal comprises an end of said first lightly doped region, said second network input terminal comprises an end of said second lightly doped region, and said network output terminal comprises another end of said first lightly doped region, another end of said second lightly doped region, and portions of said first and said second conductive plates commonly connected.
Claim 11
Dependent Claim
135 words
A comparator for data communications applications, comprising: means for accepting a differential voltage; means for producing first and second voltages from the differential voltage; resistive-capacitive network means for averaging the first and second voltages to obtain a common-mode voltage, wherein the resistance of the resistive-capacitive network is provided by a lightly doped silicon region and the capacitance of the resistive-capacitive network is provided by the lightly doped silicon region and a polysilicon region which are separated by an insulating region; means for comparing the common-mode voltage to a reference voltage; means for adjusting the first and second voltages, based upon the comparison of the common-mode voltage to the reference voltage, so that the common-mode voltage equals the reference voltage; and means for producing an output voltage as a function of the first and second voltages.
Claim 12
Dependent Claim
135 words
A comparator for data communications applications, comprising: means for accepting a differential voltage; means for producing first and second voltages from the differential voltage; resistive-capacitive network means for averaging the first and second voltages to obtain a common-mode voltage, wherein the resistance of the resistive-capacitive network is provided by a lightly doped silicon region and the capacitance of the resistive-capacitive network is provided by the lightly doped silicon region and a polysilicon region which are separated by an insulating region; means for comparing the common-mode voltage to a reference voltage; means for adjusting the first and second voltages, based upon the comparison of the common-mode voltage to the reference voltage, so that the common-mode voltage equals the reference voltage; and means for producing an output voltage as a function of the first and second voltages.
Claim 13
Dependent Claim
19 words
A comparator as in claim 7 wherein the means for comparing and means for adjusting comprises an operational amplifier.
Claim 14
Dependent Claim
119 words
A comparator for use with a data communications system, comprising: a first amplifying stage which accepts a differential voltage as comparator input and produces first and second voltages; a resistive-capacitive voltage averaging network that averages the first and second voltages to produce a third voltage, the network having two mutually coupled sections with parallel resistive-capacitive elements, the two network sections respectively accepting the first and second voltages and furnishing the third voltage where mutually coupled; and feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the first amplifying stage such that the third voltage is maintained equal to the reference voltage.
Claim 15
Dependent Claim
119 words
A comparator for use with a data communications system, comprising: a first amplifying stage which accepts a differential voltage as comparator input and produces first and second voltages; a resistive-capacitive voltage averaging network that averages the first and second voltages to produce a third voltage, the network having two mutually coupled sections with parallel resistive-capacitive elements, the two network sections respectively accepting the first and second voltages and furnishing the third voltage where mutually coupled; and feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the first amplifying stage such that the third voltage is maintained equal to the reference voltage.
Claim 16
Dependent Claim
20 words
A comparator as in claim 9, wherein the resistance of the resistive-capacitive network is between 50 and 200 kilo-ohms inclusive.
Claim 17
Dependent Claim
20 words
A comparator as in claim 10, wherein the capacitance of the resistive-capacitive network is between 1.5 and 5.0 kilo-ohms inclusive.
Claim 18
Dependent Claim
47 words
A comparator as in claim 9, wherein: the resistance of the resistive-capacitive network is provided by a lightly doped semiconductor region; and the capacitance of the resistive-capacitive network is provided by the lightly doped semiconductor region and a conductive region which are separated by an insulating region.
Claim 19
Dependent Claim
74 words
A comparator as in claim 12, wherein: the lightly doped semiconductor region further comprises a plurality of lightly doped semiconductor regions, each of the plurality of semiconductor regions connected to one or more of the other semiconductor regions by electrically conductive material; and the conductive region further comprises a plurality of conductive regions, each of the plurality of conductive regions connected to one or more of the other conductive regions by conductive connecting regions.
Claim 20
Dependent Claim
130 words
A comparator as in claim 13, wherein: each of the plurality of semiconductor regions has a length that is greater than the width, a lengthwise side of each of the semiconductor regions parallel and adjacent to a lengthwise side of one of the other semiconductor regions; each of the semiconductor regions being connected at an end or ends of the length to the other semiconductor region or regions; each of the plurality of conductive regions has a length that is greater than the width, a lengthwise side of each of the conductive regions parallel and adjacent to a lengthwise side of one of the other conductive regions; and each of the conductive regions being connected at an end or ends of the length to the other conductive region or regions.
Claim 21
Dependent Claim
79 words
A comparator as in claim 12, wherein: the lightly doped semiconductor region is a doped silicon region of a first conductivity type disposed in a body, the body being a doped silicon region of a second conductivity type that is opposite to the first conductivity type; and the capacitance of the resistive-capacitive network is primarily determined by capacitance between the lightly doped silicon region and the conductive region, and capacitance between the lightly doped silicon region and the body.
Claim 22
Dependent Claim
12 words
A comparator as in claim 15, wherein the conductive region is polysilicon.
Claim 23
Dependent Claim
61 words
A comparator as in claim 16, wherein: the insulating region comprises a thin oxide section disposed between a portion of the lightly doped silicon region and a portion of the polysilicon region, and a thick oxide section; and the capacitance between the lightly doped silicon region and the polysilicon region is controllable based on a thickness of the thin oxide section.
Claim 24
Dependent Claim
123 words
A comparator for use with a data communications system, comprising: a first amplifying stage which accepts a differential voltage as comparator input and produces first and second voltages; a voltage averaging network that averages the first and second voltages to produce a third voltage; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the first amplifying stage such that the third voltage is maintained equal to the reference voltage; and a second amplifying stage which amplifies the first and second voltages and produces an output voltage as comparator output, the second amplifying stage having a logic threshold voltage that is equal to the reference voltage.
Claim 25
Dependent Claim
123 words
A comparator for use with a data communications system, comprising: a first amplifying stage which accepts a differential voltage as comparator input and produces first and second voltages; a voltage averaging network that averages the first and second voltages to produce a third voltage; feedback control circuitry which compares the third voltage to a reference voltage and produces a fourth voltage, wherein the fourth voltage controls the flow of current in the first amplifying stage such that the third voltage is maintained equal to the reference voltage; and a second amplifying stage which amplifies the first and second voltages and produces an output voltage as comparator output, the second amplifying stage having a logic threshold voltage that is equal to the reference voltage.
Claim 26
Dependent Claim
150 words
A integrated circuit data communications comparator comprising: a first differential amplifier having first and second differential inputs, first and second differential outputs, and a bias voltage input; a network comprising first and second network sections having parallel resistive-capacitive elements and essentially identical impedance, the first and second network sections being coupled to one another at one end to provide a network output, the first network section having another end coupled to the first differential output of the first differential amplifier, and the second network section having another end coupled to the second differential output of the first differential amplifier; a reference voltage generator having an output; and a second differential amplifier having a first differential input coupled to the output of the network, a second differential input coupled to the output of the reference voltage generator, and an output coupled to the bias voltage input of the first differential amplifier.
Claim 27
Dependent Claim
150 words
A integrated circuit data communications comparator comprising: a first differential amplifier having first and second differential inputs, first and second differential outputs, and a bias voltage input; a network comprising first and second network sections having parallel resistive-capacitive elements and essentially identical impedance, the first and second network sections being coupled to one another at one end to provide a network output, the first network section having another end coupled to the first differential output of the first differential amplifier, and the second network section having another end coupled to the second differential output of the first differential amplifier; a reference voltage generator having an output; and a second differential amplifier having a first differential input coupled to the output of the network, a second differential input coupled to the output of the reference voltage generator, and an output coupled to the bias voltage input of the first differential amplifier.
Claim 28
Dependent Claim
167 words
A comparator as in claim 19 wherein the first differential amplifier comprises: a low gain amplification stage having first and second differential outputs, the first and second differential inputs of the first differential amplifier being inputs of the low gain amplification stage, and the bias voltage input of the first differential amplifier being a bias voltage input of the low gain amplification stage; a first buffer having an input coupled to the first differential output of the low gain amplification stage, an output, and a bias voltage input, the output of the first buffer being the first differential output of the first differential amplifier; and a second buffer having an input coupled to the second differential output of the low gain amplification stage, an output, and a bias voltage input, the output of the second buffer being the second differential output of the first differential amplifier; wherein the output of the second differential amplifier is coupled to the bias voltage inputs of the first and second buffers.
Claim 29
Dependent Claim
15 words
A comparator as in claim 20 wherein the first and second buffers are source followers.
Claim 30
Dependent Claim
59 words
A comparator as in claim 19 further comprising an output amplifier having an input coupled to the first differential output of the first differential amplifier, and having an output, and being characterized by a high gain region; wherein the output of the network has a voltage substantially in the center of the high gain region of the output amplifier.
Claim 31
Dependent Claim
20 words
A comparator as in claim 22 wherein the reference voltage generator and the output amplifier comprise respective essentially identical amplifiers.
Claim 32
Dependent Claim
94 words
A comparator as in claim 19 further comprising: a first output amplifier having an input coupled to the first differential output of the first differential amplifier, and having an output, and being characterized by a high gain region; and a second output amplifier having an input coupled to the second differential output of the first differential amplifier, and having an output, and being characterized by a high gain region; wherein the output of the network has a voltage substantially in the center of the high gain regions of the first and second output amplifiers.
Claim 33
Dependent Claim
25 words
A comparator as in claim 24 wherein the reference voltage generator, the first output amplifier, and the second output amplifier comprise respective essentially identical amplifiers.
Claim 34
Dependent Claim
123 words
A comparator as in claim 19 wherein the first network section comprises: a first lightly doped body region of the integrated circuit having a predetermined resistance; a first dielectric region disposed over the first lightly doped body region; and a first conductive layer disposed over the first dielectric region and cooperatively providing with the first body region a predetermined capacitance; and wherein the second network section comprises: a second lightly doped body region of the integrated circuit having a resistance equal to the predetermined resistance; a second dielectric region disposed over the second lightly doped body region; and a second conductive layer disposed over the second dielectric region and cooperatively providing with the second body region a capacitance equal to the predetermined capacitance.
Claim 35
Dependent Claim
33 words
A comparator as in claim 26 wherein the first and second body regions are essentially identical structures and are adjacent one another, and the first and second conductive layers are essentially identical structures.
References Cited (Backward Citations)
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