Hybrid binary/thermometer code for controlled-voltage integrated circuit output drivers
First Claim
1. A variable impedance network for variably adjusting the output impedance of a node of a circuit, comprising:
- one or more impedance legs electrically connected between a first voltage source and said node;
a first set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a first set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said first set of switchable impedance legs;
a second set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a second set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said second set of switchable impedance legs; and
a controller which generates said first set of calibration signals and said second set of calibration signals, wherein said controller steps said first set of calibration signals according to a binary code and steps said second set of calibration signals according to a thermometer code once per full count iteration of said first set of calibration signals.
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Accused Products
Abstract
A hybrid binary/thermometer code is employed to adjust the output impedance of a variable impedance output driver circuit having an impedance network comprising a plurality of impedance legs each programmably electrically connectable according to the hybrid binary/thermometer code in parallel between a voltage source and the signal pad. The plurality of impedance legs are partitioned into one or more set pairs of binary stepped impedance legs and corresponding thermometer stepped impedance legs. A binary set of calibration signals in the hybrid binary/thermometer code steps a given set of binary stepped impedance legs according to a binary code and a thermometer set of calibration signals in the hybrid binary/thermometer code steps the corresponding set of thermometer stepped impedance legs according to a thermometer code once per full count iteration of the binary set of calibration signals.
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Citations
23 Claims
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1. A variable impedance network for variably adjusting the output impedance of a node of a circuit, comprising:
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one or more impedance legs electrically connected between a first voltage source and said node;
a first set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a first set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said first set of switchable impedance legs;
a second set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a second set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said second set of switchable impedance legs; and
a controller which generates said first set of calibration signals and said second set of calibration signals, wherein said controller steps said first set of calibration signals according to a binary code and steps said second set of calibration signals according to a thermometer code once per full count iteration of said first set of calibration signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for variably adjusting the output impedance of a node of a circuit, said circuit comprising an impedance network interposed between a voltage source and said node, said impedance network comprising one or more impedance legs electrically connected between said first voltage source and said node, a first set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a first set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said first set of switchable impedance legs, and a second set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a second set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said second set of switchable impedance legs, said method comprising the steps of:
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stepping said first set of calibration signals according to a binary code; and
stepping said second set of calibration signals according to a thermometer code once per full count iteration of said first set of calibration signals. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A variable impedance network for variably adjusting the output impedance of a node of a circuit, comprising:
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one or more impedance legs electrically connected between a first voltage source and said node;
a first set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a first set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said first set of switchable impedance legs;
a second set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a second set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said second set of switchable impedance legs;
a third set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a third set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said third set of switchable impedance legs;
a fourth set of switchable impedance legs programmably electrically connectable between said voltage source and said node by a fourth set of calibration signals each of which corresponds to a respective one or more of said switchable impedance legs in said fourth set of switchable impedance legs;
wherein said first set of calibration signals, said second set of calibration signals, said third set of calibration signals, and said fourth set of calibration signals represent bits with different respective predetermined bit positions in a calibration word, and wherein each of said first set of switchable impedance legs and each of said third set of switchable impedance legs is binary weighted according to the bit position of its corresponding calibration signal in the calibration word; and
a controller which generates said first set of calibration signals, said second set of calibration signals, said third set of calibration signals, and said fourth set of calibration signals;
wherein said controller steps said first set of calibration signals according to a binary code and steps said second set of calibration signals according to a thermometer code once per full count iteration of said first set of calibration signals, and steps said first set of calibration signals and said third set of calibration signals, taken as a combination, according to a binary code and steps said fourth set of calibration signals according to a thermometer code once per full count iteration of said combination of said first set of calibration signals and said third set of calibration signals.
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16. A method for stepping a hybrid binary/thermometer code, said code comprising a first set of binary bits each with a predetermined bit position in said code and a first set of thermometer bits each with a different predetermined bit position in said code, said method comprising the steps of:
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for each incrementing step of said hybrid binary/thermometer code;
incrementing said first set of binary bits according to a binary increment; and
if said first set of thermometer bits is not fully incremented, incrementing said first set of thermometer bits according to a thermometer code increment upon overflow of said first set of binary bits. - View Dependent Claims (17, 18, 19)
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20. A method for stepping a hybrid binary/thermometer code, said code comprising a first set of binary bits each with a predetermined bit position in said code and a first set of thermometer bits each with a different predetermined bit position in said code, said method comprising the steps of:
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for each incrementing step of said hybrid binary/thermometer code;
incrementing said first set of binary bits according to a binary increment; and
if said first set of thermometer bits is not fully incremented, incrementing said first set of thermometer bits according to a thermometer code increment upon overflow of said first set of binary bits. - View Dependent Claims (21, 22, 23)
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Specification