Abstract: The present invention provides an amplifier circuit comprising a differential amplifier and a negative feedback loop circuit, in which a positive feedback loop circuit having a gain smaller than a gain of the negative feedback loop circuit is formed inside the negative feedback loop circuit.

Abstract: A gain adjustment circuit includes a gain varying device for varying the gain of an input signal; and a detection device for detecting a variable output signal of the gain varying device, wherein the detection output signal of the detection device is fed back to the gain varying device.

Abstract: The present invention provides an amplifier circuit comprising a differential amplifier and a negative feedback loop circuit, in which a positive feedback loop circuit having a gain smaller than a gain of the negative feedback loop circuit is formed inside the negative feedback loop circuit.

Abstract: The present invention provides an amplifier circuit comprising a differential amplifier and a negative feedback loop circuit, in which a positive feedback loop circuit having a gain smaller than a gain of the negative feedback loop circuit is formed inside the negative feedback loop circuit.

Abstract: A gain adjustment circuit includes a gain varying device for varying the gain of an input signal; and a detection device for detecting a variable output signal of the gain varying device, wherein the detection output signal of the detection device is fed back to the gain varying device.

Abstract: The present invention provides an amplifier circuit comprising a differential amplifier and a negative feedback loop circuit, in which a positive feedback loop circuit having a gain smaller than a gain of the negative feedback loop circuit is formed inside the negative feedback loop circuit.

Abstract: An asymmetry detection circuit having a simple circuit configuration capable of realizing reliable detection without dependence on the signal level and capable of realizing high precision asymmetry detection almost completely free of any influence from a voltage offset or the like, and a detection method of same, wherein a capacitor cuts off the direct current component of an input signal and passes the alternating current component, a bias voltage is added to the alternating current component in accordance with a constant voltage of a constant voltage source to generate an APL clamp signal, a comparator compares the signal with a constant voltage and outputs a pulse voltage signal representing a duty ratio of the signal in the APL value, a voltage/current conversion circuit outputs a current signal to charge or discharge a capacitor to generate an integrated signal, and a filter eliminates the alternating current component of the integrated signal and outputs the direct current component as an asymmetry dete

Abstract: A nonlinearity compensation circuit is disclosed which includes an inverse hyperbolic function generation circuit for converting differential currents corresponding to input signals in+ and in− into differential voltages which increase in proportion to an inverse hyperbolic function, an offset provision circuit for providing an offset corresponding to control signals c+ and c− to the differential voltages outputted from the inverse hyperbolic function generation circuit and a hyperbolic function generation circuit for converting the differential voltages to which the offset has been provided by the offset provision circuit into signals which increase in proportion to a hyperbolic function and outputting the resulting signals as output signals out+ and out−. Consequently, compensation for the nonlinearity such as second order distortion can be performed for the read signal from a recording medium.

Abstract: A nonlinearity compensation circuit is disclosed which includes an inverse hyperbolic function generation circuit for converting differential currents corresponding to input signals in+ and in− into differential voltages which increase in proportion to an inverse hyperbolic function, an offset provision circuit for providing an offset corresponding to control signals c+ and c− to the differential voltages outputted from the inverse hyperbolic function generation circuit and a hyperbolic function generation circuit for converting the differential voltages to which the offset has been provided by the offset provision circuit into signals which increase in proportion to a hyperbolic function and outputting the resulting signals as output signals out+ and out−. Consequently, compensation for the nonlinearity such as second order distortion can be performed for the read signal from a recording medium.

Abstract: An asymmetry detection circuit having a simple circuit configuration, capable of realizing reliable detection without dependance on the signal level, and capable of realizing high precision asymmetry detection almost completely free of any influence from a voltage offset or the like, and a detection method of same, wherein a capacitor cuts off a direct current component of an input signal and passes alternating current component, a bias voltage is added to the alternating current component in accordance with a constant voltage of a constant voltage source to generate an APL clamp signal, a comparator compares the signal with a constant voltage and outputs a pulse voltage signal representing a duty ratio of the signal in the APL value, a voltage/current conversion circuit outputs a current signal to charge or discharge a capacitor to generate an integrated signal, and a filter eliminates the alternating current component of the integrated signal and outputs the direct current component as an asymmetry detectio