Semiconductor device with automatic impedance adjustment circuit
First Claim
1. A semiconductor device connected to a bus having a plurality of signal lines, the semiconductor device comprising:
- a resistor having a first end connected to a ground voltage;
a first pad connected to a second end of the resistor;
a plurality of second pads respectively connected to the plurality of signal lines;
a reference voltage generator for generating a reference voltage;
a comparator for comparing the voltage at the first pad with the reference voltage to generate a control signal;
a code generator for generating a code signal in response to the control signal;
a current source for supplying the first pad with a variable current in accordance with the code signal; and
a data driver for driving data signals onto the signal lines via the second pads in accordance with the code signal.
1 Assignment
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Accused Products
Abstract
A semiconductor device connected to a bus consisting of a plurality of signal lines, comprises a first pad connected with a discrete resistor corresponding to the impedance of the signal lines, a plurality of second pads respectively connected with the signal lines, a reference voltage generator for generating a reference voltage, a comparator for comparing the voltage on the first pad with the reference voltage to generate a control signal, a code generator for generating a code signal according to the control signal, a current source for supplying the first pad with variable current according to the code signal, and a data driver for driving data signals to the signal lines connected with the second pads according to the code signal. The code signal is used to match the impedance of the data driver with the impedance of the signal lines.
35 Citations
14 Claims
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1. A semiconductor device connected to a bus having a plurality of signal lines, the semiconductor device comprising:
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a resistor having a first end connected to a ground voltage; a first pad connected to a second end of the resistor; a plurality of second pads respectively connected to the plurality of signal lines; a reference voltage generator for generating a reference voltage; a comparator for comparing the voltage at the first pad with the reference voltage to generate a control signal; a code generator for generating a code signal in response to the control signal; a current source for supplying the first pad with a variable current in accordance with the code signal; and a data driver for driving data signals onto the signal lines via the second pads in accordance with the code signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A semiconductor device connected to a bus having of a plurality of signal lines, the semiconductor device comprising:
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a discrete resistor corresponding to the impedance of the signal lines; a first pad connected to the discrete resistor; a plurality of second pads respectively connected with the signal lines; an impedance adjustment circuit connected to the first pad to generate a code signal according to the value of the discrete resistor; and a data driver for driving data signals to the signal lines in response to the code signal, the impedance of the data driver being adjusted to have the same value as that of the signal lines. - View Dependent Claims (14)
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Specification