Impedance control circuit for controlling multiple different impedances with single control circuit
First Claim
1. An impedance control circuit comprising:
- a reference voltage output circuit for outputting one of a plurality of reference voltages;
a variable resistor;
a comparator that has a first input terminal supplied with a reference voltage from said reference voltage output circuit and a second input terminal connected to said variable resistor, wherein the comparator compares the voltages supplied to the first and second input terminals;
a control circuit for controlling said variable resistor and for establishing a plurality of impedances corresponding to the plurality of reference voltages in response to a signal output from said comparator; and
a calculation circuit for establishing an impedance with a desired value using a plurality of resistances of said variable resistor corresponding to the plurality of reference voltages.
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0 Petitions
Accused Products
Abstract
An impedance control circuit includes a reference voltage output circuit for outputting one of a plurality of reference voltages; a variable resistor; a comparator and a control circuit. The comparator includes a first input terminal supplied with a reference voltage from the reference voltage output circuit and a second input terminal connected to the variable resistor, and compares the voltages at the first and second input terminals. The control circuit controls the variable resistor and establishes a plurality of impedances corresponding to the reference voltages in response to the signal output from the comparator. It enables the single impedance control circuit to control the plurality of different impedances on the semiconductor integrated circuit.
73 Citations
8 Claims
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1. An impedance control circuit comprising:
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a reference voltage output circuit for outputting one of a plurality of reference voltages;
a variable resistor;
a comparator that has a first input terminal supplied with a reference voltage from said reference voltage output circuit and a second input terminal connected to said variable resistor, wherein the comparator compares the voltages supplied to the first and second input terminals;
a control circuit for controlling said variable resistor and for establishing a plurality of impedances corresponding to the plurality of reference voltages in response to a signal output from said comparator; and
a calculation circuit for establishing an impedance with a desired value using a plurality of resistances of said variable resistor corresponding to the plurality of reference voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification