Differential amplifier, comparator and high-speed A/D converter using the same

A differential amplifier comprising:

• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to an analog input signal for supplying an increasing current to said first constant current source,
• decreasing current supplying means responsive to another analog input signal for supplying a decreasing current to said first constant current source,
• said first predetermined constant current being a sum of said increasing current and said decreasing current,
• first constant current supplying means responsive to a first applied reference voltage for supplying a third predetermined constant current to said second constant current source,
• second constant current supplying means responsive to a second applied reference voltage for supplying a fourth predetermined constant current to said second constant current source,
• said second predetermined constant current being a sum of said third and fourth constant currents,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second constant current supplying means,
• second load means having one end connected to the power source potential and the other end connected to said decreasing current supplying means and said first constant current supplying means, wherein a differential output voltage is output through the other ends of each of said first and second load means, and
• proportional range expanding means for expanding a range of a difference between said first and second differential input voltages wherein currents applied by said first and second proportional current supplying means can be proportional to each other,
• wherein said analog input signal includes first and second differential input voltages,
• said increasing current supplying means includes first proportional current supplying means responsive to the first differential input voltage for supplying, to said first constant current source, a current proportional to said first differential input voltage, and
• said decreasing current supplying means includes second proportional current supplying means responsive to the second differential input voltage for supplying, to said second constant current source, a current proportional to said second differential input voltage.

A differential amplifier comprising:

• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to an analog input signal for supplying an increasing current to said first constant current source,
• decreasing current supplying means responsive to the analog input signal for supplying a decreasing current to said first constant current source,
• said first predetermined constant current being a sum of said increasing current and said decreasing current,
• first constant current supplying means responsive to a first applied reference voltage for supplying a third predetermined constant current to said second constant current source,
• second constant current supplying means responsive to a second applied reference voltage for supplying a fourth predetermined constant current to said second constant current source,
• said second predetermined constant current being a sum of said third and fourth constant currents,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second constant current supplying means,
• second load means having one end connected to the power source potential and the other end connected to said decreasing current supplying means and said first constant current supplying means, wherein a differential output voltage is output through the other ends of each of said first and second load means, and
• first switching means connected between said increasing current supplying means, said decreasing current supplying means and said first constant current source and operable in response to an applied control signal.

A comparator comprising

• a differential amplifier including;
• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to an analog input signal for supplying an increasing current to said first constant current source,
• decreasing current supplying means responsive to the analog input signal for supplying a decreasing current to said first constant current source,
• said first predetermined constant current being a sum of said increasing current and said decreasing current,
• first constant current supplying means responsive to another first applied reference voltage for supplying a third predetermined constant current to said second constant current source,
• second constant current supplying means responsive to a second applied reference voltage for supplying a fourth predetermined constant current to said second constant current source,
• said second predetermined constant current being a sum of said third and fourth constant currents,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second constant current supplying means, and
• second load means having one end connected to the power source potential and the other end connected to said decreasing current supplying means, wherein a differential output voltage is output through the other ends of each of said first and second load means, and
• binarizing means responsive to a differential output signal output from said differential amplifier for generating a binarization signal.

An A/D converter comprising:

• differential signal generating means responsive to an analog input signal and another analog input signal for generating first and second differential signals,
• reference voltage generating means for generating first and second reference voltages for defining a predetermined larger potential difference and third and fourth reference voltages for defining a predetermined smaller potential difference,
• first comparator means for comparing a voltage difference between the first and the second differential signals with a difference between the first and the second reference voltages, and
• second comparator means for comparing the voltage difference between the first and the second differential signals with a difference between the third and the fourth reference voltages, each of said first and second comparator means including:
• a differential amplifier comprising:
• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to the analog input signal for supplying an increasing current to said first constant current source,
• decreasing current supplying means responsive to the another analog input signal for supplying a decreasing current to said first constant current source,
• said first predetermined constant current being a sum of said increasing current and said decreasing current,
• first constant current supplying means responsive to a first applied reference voltage for supplying a third predetermined constant current to said second constant current source,
• second constant current supplying means responsive to a second applied reference voltage for supplying a fourth predetermined constant current to said second constant current source,
• said second predetermined constant current being a sum of said third and fourth constant currents,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second constant current supplying means, and
• second load means having one end connected to the power source potential and the other end connected to said decreasing current supplying means, wherein a differential output voltage is output through the other ends of each of said first and second load means, and
• binarizing means responsive to a differential output signal output from said differential amplifier for generating a binarization signal.

An A/D converter comprising:

• differential signal generating means responsive to an analog input signal and another analog input signal for generating first and second differential signals,
• reference voltage pair generating means for generating at least one reference voltage pair whose voltage difference is sequentially reduced, and
• at least one comparator means each for receiving said first and second differential signals and corresponding one of said at least one reference voltage pairs and comparing a voltage difference between said first and second differential signals with a voltage difference between the voltages of said corresponding reference voltage pair, each of said at least one comparator means including:
• a differential amplifier comprising:
• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to the analog input signal for supplying an increasing current to said first constant current source,
• decreasing current supplying means responsive to the another analog input signal for supplying a decreasing current to said first constant current source,
• said first predetermined constant current being a sum of said increasing current and said decreasing current,
• first constant current supplying means responsive to a first applied reference voltage for supplying a third predetermined constant current to said second constant current source,
• second constant current supplying means responsive to a second applied reference voltage for supplying a fourth predetermined constant current to said second constant current source,
• said second predetermined constant current being a sum of said third and fourth constant currents,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second constant current supplying means, and
• second load means having one end connected to the power source potential and the other end connected to said decreasing current supplying means, wherein a differential output voltage is output through the other ends of each of said first and second load means, and
• binarizing means responsive to a differential output signal output from said differential amplifier for generating a binarization signal.

A differential amplifier including:

• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to an analog input signal for supplying an increasing current to said first constant current source,
• first compensation current supplying means for supplying a first compensation current to said first constant current source,
• decreasing current supplying means responsive to another analog input signal for supplying a decreasing current to said first constant current source,
• second compensation current supplying means for supplying a second compensation current to said second constant current source,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second compensation current supplying means, and
• second load means having one end connected to the power source potential and the other end connected to said decreasing current supplying means and said first compensation current supplying means, wherein a differential output voltage representing a difference between the analog input signal and the another analog input signal is output through an output end of each of said first and second load means.

A comparator comprising:

• a differential amplifier including:
• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to an analog input signal for supplying an increasing current to said first constant current source,
• first compensation current supplying means for supplying a first compensation current to said first constant current source,
• decreasing current supplying means responsive to another analog input signal for supplying the decreasing current to said second constant current source,
• second compensation current supplying means for supplying a second compensation current to said second constant current source,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second compensation current supplying means, and
• second load means having one end connected to a power source potential and the other end connected to said decreasing current supplying means and said first compensation current supplying means, wherein a differential output voltage representing a difference between the analog input signal and the another analog input signal is output through an output end of each of said first and second load means, and
• binarizing means responsive to a differential output signal output from said differential amplifier for generating a binary signal.

An A/D converter comprising:

• differential signal generating means responsive to an analog input signal and another analog input signal for generating first and second differential signals,
• reference voltage pair generating means for generating first and second reference voltages for defining a predetermined larger potential difference and third and fourth reference voltages for defining a predetermined smaller potential difference,
• first comparator means each for comparing a voltage difference between the first and the second differential signals with a difference between the first and the second reference voltages, and
• second comparator means for comparing the voltage difference between the first and the second differential signals with a difference between the third and the fourth reference voltages, each of said first and second comparator means including:
• a differential amplifier including:
• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to the analog input signal for supplying an increasing current to said first constant current source,
• first compensation current supplying means for supplying a first compensation current to said first constant current source,
• decreasing current supplying means responsive to the another analog input signal for supplying the decreasing current to said second constant current source,
• second compensation current supplying means for supplying a second compensation current to said second constant current source,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second compensation current supplying means, and
• second load means having one end connected to a power source potential and the other end connected to said decreasing current supplying means and said first compensation current supplying means, wherein a differential output voltage representing a difference between the analog input signal and the another analog input signal is output through an output end of each of said first and second load means, and
• binarizing means responsive to a differential output signal output from said differential amplifier for generating a binary signal.

An A/D converter comprising:

• differential signal generating means responsive to an analog input signal and another analog input signal for generating first and second differential signals,
• reference voltage pair generating means for generating at least one reference voltage pair whose voltage difference is sequentially reduced, and
• at least one comparator means each for receiving said first and second differential signals and a corresponding one of said at least one reference voltage pairs and comparing a voltage difference between said first and second differential signals with a voltage difference between the voltages of said corresponding reference voltage pair, each of said at least one comparator means including:
• a differential amplifier including:
• a first constant current source for conducting a flow of a first predetermined constant current,
• a second constant current source for conducting a flow of a second predetermined constant current,
• increasing current supplying means responsive to the analog input signal for supplying an increasing current to said first constant current source,
• first compensation current supplying means for supplying a first compensation current to said first constant current source,
• decreasing current supplying means responsive to the another analog input signal for supplying the decreasing current to said second constant current source,
• second compensation current supplying means for supplying a second compensation current to said second constant current source,
• first load means having one end connected to a power source potential and the other end connected to said increasing current supplying means and said second compensation current supplying means, and
• second load means having one end connected to a power source potential and the other end connected to said decreasing current supplying means and said first compensation current supplying means, wherein a differential output voltage representing a difference between the analog input signal and the another analog input signal is output through an output end of each of said first and second load means, and
• binarizing means responsive to a differential output signal output from said differential amplifier for generating a binary signal.

A differential amplifier, comprising:

• first and second constant current sources,
• first and second compensation current supplying means for supplying first and second compensation currents to said first and second constant current sources respectively, and said first and second compensation current supplying means receiving first and second reference signals respectively,
• increasing current supplying means, responsive to a first analog input signal, for supplying an increasing current to said first constant current source,
• decreasing current supplying means responsive to a second analog input signal for supplying a decreasing current to said first constant current source,
• first load means, connected to a power source potential, connected to said increasing current supplying means and connected to said second compensation current supplying means, for providing a first differential output voltage responsive to said first and second analog input signals, and
• second load means, connected to the power source potential, connected to said decreasing current supplying means and connected to said first compensation current supplying means, for providing a second differential output voltage responsive to said first and second reference signals.