Abstract: A compensation apparatus is provided which performs a compensation process of removing an image component in a quadrature-demodulated signal. The compensation apparatus includes a quadrature demodulation compensation section that compensates for the quadrature-demodulated signal including an I signal and a Q signal. The quadrature demodulation compensation section is configured to perform a compensation process of compensating for a characteristic difference between the frequency characteristic of a first filter that performs filtering of the I signal and the frequency characteristic of a second filter that performs filtering of the Q signal.

Abstract: A compensation apparatus compensates a quadrature-demodulated signal output from a quadrature demodulator 5 that performs quadrature demodulation by using a signal of a carrier frequency fc, by removing an image component caused by the quadrature demodulator 5 from the quadrature-demodulated signal. The compensation apparatus includes a signal generator 10 that generates a reference signal having a predetermined bandwidth in a reception band, and provides the reference signal to an input side of the quadrature demodulator 5. The reference signal includes a frequency band that is biased to either a higher-frequency side or a lower-frequency side with respect to the carrier frequency.

Abstract: A distortion compensation apparatus that compensates for distortion of an amplifier is provided. The distortion compensation apparatus includes: a distortion compensation processing section that performs a predistortion process for a signal provided to the amplifier, based on an amplifier model of the amplifier, and outputs a compensated signal; an estimation section that estimates the amplifier model; and a filter. The estimation section estimates the amplifier model, based on the compensated signal and a monitor signal obtained by monitoring an output of the amplifier. The monitor band of the monitor signal provided to the estimation section is narrower than a frequency band of the compensated signal. The filter is provided so as to eliminate an influence of a signal component outside the monitor band among signal components of the compensated signal, on the estimation of the amplifier model by the estimation section.

Abstract: A compensation apparatus is provided which performs a compensation process of removing an image component in a quadrature-demodulated signal. The compensation apparatus includes a quadrature demodulation compensation section that compensates for the quadrature-demodulated signal including an I signal and a Q signal. The quadrature demodulation compensation section is configured to perform a compensation process of compensating for a characteristic difference between the frequency characteristic of a first filter that performs filtering of the I signal and the frequency characteristic of a second filter that performs filtering of the Q signal.

Abstract: A compensation apparatus compensates a quadrature-demodulated signal output from a quadrature demodulator 5 that performs quadrature demodulation by using a signal of a carrier frequency fc, by removing an image component caused by the quadrature demodulator 5 from the quadrature-demodulated signal. The compensation apparatus includes a signal generator 10 that generates a reference signal having a predetermined bandwidth in a reception band, and provides the reference signal to an input side of the quadrature demodulator 5. The reference signal includes a frequency band that is biased to either a higher-frequency side or a lower-frequency side with respect to the carrier frequency.

Abstract: In a method for producing a semiconductor light emitting device: a semiconductor lamination of first and second semiconductor layers having different conductive types is formed; a portion of the semiconductor lamination is removed to expose an area of a surface of the first semiconductor layer; a conductor layer connecting the first and second semiconductor layers is formed; a first electrode is formed on the exposed areas of the first semiconductor layer and a second electrode is formed on an upper surface of the second semiconductor layer; a barrier layer covering at least one of the first and second electrodes is formed; and a connection part in the conductor layer connecting the first and second semiconductor layers is removed.

Abstract: A nitride group semiconductor light emitting device includes a nitride group semiconductor layer, and an electrode structure. The electrode structure is arranged on or above the semiconductor layer, and includes a plurality of deposited metal layers. The plurality of deposited metal layers of the electrode structure includes first and second metal layers. The first metal layer is arranged on the semiconductor layer side. The second metal layer is arranged on or above the first metal layer. The first metal layer contains Cr, and a first metal material. The first metal material has a reflectivity higher than Cr at the light emission peak wavelength of the light emitting device. According to this construction, the first metal layer can have a higher reflectivity as compared with the case where the first metal layer is only formed of Cr, but can keep tight contact with the semiconductor layer.

Abstract: In a method for producing a semiconductor light emitting device: a semiconductor lamination of first and second semiconductor layers having different conductive types is formed; a portion of the semiconductor lamination is removed to expose an area of a surface of the first semiconductor layer; a conductor layer connecting the first and second semiconductor layers is formed; a first electrode is formed on the exposed areas of the first semiconductor layer and a second electrode is formed on an upper surface of the second semiconductor layer; a barrier layer covering at least one of the first and second electrodes is formed; and a connection part in the conductor layer connecting the first and second semiconductor layers is removed.

Abstract: A quadrature modulation error is compensated without providing an additional feedback loop for detecting quadrature modulation error. An amplifier circuit includes: a quadrature modulator; an amplifier that amplifies a quadrature-modulated signal; a distortion compensation section that compensates distortion to be caused in the amplifier based on first compensation coefficients; a quadrature modulation error compensation section that compensates for a quadrature modulation error; an updating section that updates second compensation coefficients for compensating the quadrature modulation error; an error estimation section that estimates an error of the quadrature modulation error; and a prediction section that calculates a prediction value of an output of the amplifier after updating of the second compensation coefficients. The second compensation coefficients are updated based on the estimated error. The prediction value is calculated based on the estimated error and the amplifier output.

Abstract: Signal timing adjustment in an amplifying device is appropriately performed by phase adjustment by a digital filter. The amplifying device includes an amplifier; an amplitude-voltage converting unit 12 that performs a desired process on a signal relating to operation of the amplifier, whereby the signal is band-broadened; and a timing adjusting unit 15a that performs timing adjustment of the signal to be provided to the amplifier, by phase adjustment by a digital filter. The timing adjusting unit 15a performs the timing adjustment of the signal at a stage before the signal is band-broadened by the amplitude-voltage converting unit 12.

Abstract: A compensation apparatus compensates a quadrature-demodulated signal output from a quadrature demodulator 5 that performs quadrature demodulation by using a signal of a carrier frequency fc, by removing an image component caused by the quadrature demodulator 5 from the quadrature-demodulated signal. The compensation apparatus includes a signal generator 10 that generates a reference signal having a predetermined bandwidth in a reception band, and provides the reference signal to an input side of the quadrature demodulator 5. The reference signal includes a frequency band that is biased to either a higher-frequency side or a lower-frequency side with respect to the carrier frequency.

Abstract: A quadrature modulation error is compensated without providing an additional feedback loop for detecting quadrature modulation error. An amplifier circuit includes: a quadrature modulator; an amplifier that amplifies a quadrature-modulated signal; a distortion compensation section that compensates distortion to be caused in the amplifier based on first compensation coefficients; a quadrature modulation error compensation section that compensates for a quadrature modulation error; an updating section that updates second compensation coefficients for compensating the quadrature modulation error; an error estimation section that estimates an error of the quadrature modulation error; and a prediction section that calculates a prediction value of an output of the amplifier after updating of the second compensation coefficients. The second compensation coefficients are updated based on the estimated error. The prediction value is calculated based on the estimated error and the amplifier output.

Abstract: An amplifier circuit of envelope tracking scheme has a timing adjusting unit having a finite number of adjustment values for adjusting time by which the output is delayed from the input, and capable of adjusting a time difference between an input signal and a power supply voltage which reach an amplifier, by making a selection from the adjustment values; a test signal output unit capable of repeatedly sending out a test signal serving as the input signal at predetermined cycles; and an adjustment value determining unit sequentially measuring output power for m (?k) periods from the amplifier while changing an adjustment value of the timing adjusting unit to a different value every k periods of the test signal, searching for an adjustment value at which a total sum of the output power form periods is maximum, and setting the adjustment value on the timing adjusting unit.

Abstract: To provide a method of manufacturing a nitride semiconductor light emitting element, which has a small number of steps and thus, can improve productivity, the method of manufacturing a nitride semiconductor light emitting element including a nitride semiconductor light emitting element structure having an n-type nitride semiconductor layer and a p-side nitride semiconductor layer which are laminated on a substrate, an n-side pad electrode connecting surface and a p-side pad electrode connecting surface which are formed on the same plane of the substrate; a n-side pad electrode on the n-side pad electrode connecting surface; and a p-side pad electrode on the p-side pad electrode connecting surface, and in the manufacturing method, a pad electrode layer forming step, a resist pattern forming step, a pad electrode layer etching step, a protective layer forming step and a resist pattern removing step are sequentially performed.

Abstract: Distortion compensation is performed taking into account a memory effect that occurs in a signal path other than an input-to-output path of an amplifier. An amplifier circuit 1 includes an amplifier 2 that amplifies a signal, a variable power supply 3 that varies a power supply voltage of the amplifier 2 in accordance with envelope change, and a distortion compensation section 4 that performs compensation for distortion characteristics. The distortion compensation section 4 performs the distortion compensation, based on an amplifier model which represents a memory effect that occurs on a path from a signal input port 2a of the amplifier 2 to a signal output port 2b thereof, and a memory effect that occurs on a path from a power supply port 2c of the amplifier 2 to the signal output port 2b thereof.

Abstract: A nitride group semiconductor light emitting device includes a nitride group semiconductor layer, and an electrode structure. The electrode structure is arranged on or above the semiconductor layer, and includes a plurality of deposited metal layers. The plurality of deposited metal layers of the electrode structure includes first and second and metal layers. The first metal layer is arranged on the semiconductor layer side. The second metal layer is arranged on or above the first metal layer. The first metal layer contains Cr, and a first metal material. The first metal material has a reflectivity higher than Cr at the light emission peak wavelength of the light emitting device. According to this construction, the first metal layer can have a higher reflectivity as compared with the case where the first metal layer is only formed of Cr, but can keep tight contact with the semiconductor layer.

Abstract: Disclosed is a distortion compensation circuit that efficiently compensates for distortion. A distortion compensation circuit (20) comprises a sampling memory unit (21), which accumulates an input signal and an output signal from an amplifier (4), a model estimation unit (22), which reads the input and output signals that are accumulated upon the sampling memory unit (21), estimates a model that represents an input/output characteristic of the amplifier (4), and outputs a coefficient that denotes the model thus estimated, and a distortion compensation unit (23), which compensates for a distortion of the amplifier (4), based on the coefficient.

Abstract: A distortion compensation circuit capable of realizing highly accurate distortion compensation by updating a model even under a situation in which the appearance frequency of an input signal having a maximum value is low. A DPD processor 2 includes an inverse model estimation unit 22, which estimates an inverse model for a model expressing input-output characteristics of an HPA 6 based on an input signal S1 to the HPA 6 and an output signal S10 from the HPA 6, a distortion compensation unit 26, which compensates for distortion of the input-output characteristics by adding the inverse model to the input signal S1, and a sampling circuit 20, which samples the signals S2 and S10 in a predetermined time immediately before the sampling and inputs the signals S2 and S10 to the inverse model estimation unit 22.

Abstract: An amplifier circuit of envelope tracking has a timing adjusting unit having a finite number of adjustment values for adjusting time by which the output is delayed from the input, and capable of adjusting a time difference between an input signal and a power supply voltage which reach an amplifier, by making a selection from the adjustment values; a test signal output unit capable of repeatedly sending out a test signal serving as the input signal at predetermined cycles; and an adjustment value determining unit sequentially measuring output power for m (?k) periods from the amplifier while changing an adjustment value of the timing adjusting unit to a different value every k period of the test signal, searching for an adjustment value at which a total sum of the output power for m periods is maximum, and setting the adjustment value on the timing adjusting unit.

Abstract: To provide a method of manufacturing a nitride semiconductor light emitting element, which has a small number of steps and thus, can improve productivity, the method of manufacturing a nitride semiconductor light emitting element including a nitride semiconductor light emitting element structure having an n-type nitride semiconductor layer and a p-side nitride semiconductor layer which are laminated on a substrate, an n-side pad electrode connecting surface and a p-side pad electrode connecting surface which are formed on the same plane of the substrate; a n-side pad electrode on the n-side pad electrode connecting surface; and a p-side pad electrode on the p-side pad electrode connecting surface, and in the manufacturing method, a pad electrode layer forming step, a resist pattern forming step, a pad electrode layer etching step, a protective layer forming step and a resist pattern removing step are sequentially performed.