D/A converter for a digital signal after non-linear A/D conversion, audio signal processing circuit and liquid crystal display device including the same
First Claim
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1. A D/A converter comprising:
- a first reference voltage;
a second reference voltage;
a plurality of resistors connected in series between the first reference voltage and the second reference voltage; and
a plurality of switching elements;
wherein the plurality of switching elements are controlled by an input digital data,wherein the plurality of switching elements extract a potential from selected one of connecting portions between the plurality of resistors,wherein the input digital data is a non-linear conversion digital signal,wherein the non-linear conversion digital signal is non-linear with respect to an original analog signal,wherein the potential is a linear conversion analog signal,wherein a resistance value of each of the plurality of resistors is set so that the non-linear conversion digital signal is directly converted to the linear conversion analog signal, andwherein the linear conversion analog signal is linear with respect to the original analog signal.
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Abstract
A D/A converter inputted with non-linear conversion digital data such as a digital signal encoded according to a μ-Law system or the like as it is to convert into an analog signal. A D/A converter is of resistor string type, in which a resistance value of each of resistors of a resistor string is not set uniform but weighted so that a non-linear relationship between an encoded input digital signal and an output analog signal is converted into a linear relationship. Consequently, a decode circuit for converting non-linear conversion digital data into linear conversion digital data is not required.
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Citations
16 Claims
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1. A D/A converter comprising:
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a first reference voltage; a second reference voltage; a plurality of resistors connected in series between the first reference voltage and the second reference voltage; and a plurality of switching elements; wherein the plurality of switching elements are controlled by an input digital data, wherein the plurality of switching elements extract a potential from selected one of connecting portions between the plurality of resistors, wherein the input digital data is a non-linear conversion digital signal, wherein the non-linear conversion digital signal is non-linear with respect to an original analog signal, wherein the potential is a linear conversion analog signal, wherein a resistance value of each of the plurality of resistors is set so that the non-linear conversion digital signal is directly converted to the linear conversion analog signal, and wherein the linear conversion analog signal is linear with respect to the original analog signal. - View Dependent Claims (2, 3, 4)
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5. An audio signal processing circuit comprising:
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a memory circuit storing an input digital audio data; a D/A converter comprising; a first reference voltage; a second reference voltage; a plurality of resistors connected in series between the first reference voltage and the second reference voltage; and a plurality of switching elements; an analog circuit connected to the D/A converter; and a control circuit connected to the memory circuit and the D/A converter; wherein the plurality of switching elements are controlled by an input digital audio data, wherein the plurality of switching elements extract a potential from selected one of connecting portions between the plurality of resistors, wherein the input digital audio data is a non-linear conversion digital signal, wherein the non-linear conversion digital signal is non-linear with respect to an original analog signal, wherein the potential is a linear conversion analog signal, wherein a resistance value of each of the plurality of resistors is set so that the non-linear conversion digital signal is directly converted to the linear conversion analog signal, and wherein the linear conversion analog signal is linear with respect to the original analog signal. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A liquid crystal display device comprising:
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a substrate; a pixel portion having a first thin film transistor formed over the substrate; a driver circuit portion having a second thin film transistor formed over the substrate, connected to the pixel portion; an opposing substrate provided opposite to the substrate; a sealing member provided between the substrate and the opposing substrate; liquid crystal provided in a region surrounded by the substrate, the opposing substrate and the sealing member, and an audio signal processing circuit formed over the substrate comprising; a memory circuit storing an input digital audio data; a D/A converter comprising; a first reference voltage; a second reference voltage; a plurality of resistors connected in series between the first reference voltage and the second reference voltage; and a plurality of switching elements; an analog circuit connected to the D/A converter; and a control circuit connected to the memory circuit and the D/A converter; wherein the plurality of switching elements are controlled by an input digital audio data, wherein the plurality of switching elements extract a potential from selected one of connecting portions between the plurality of resistors, wherein the input digital audio data is a non-linear conversion digital signal, and wherein resistance values of the plurality of resistors are set so that the potential is a linear conversion analog audio signal. - View Dependent Claims (13, 14, 15, 16)
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Specification