Patent ID: 7817725

Claim:
A data converter device for performing a predetermined data conversion operation on a discretized input signal which is quadrature data to output a discretized output signal, the data converter device comprising: a first operational section for increasing a discrete value interval between amplitude components of the input signal to produce an output signal having a lower resolution amplitude-component-wise than that of the input signal; a second operational section for subtracting the input signal from the output signal having a lower resolution produced by the first operational section to extract quantization noise components generated in the first operational section; a third operational section that includes a filter for extracting, from the quantization noise components extracted by the second operational section, quantization noise components near an intended wave frequency being a center frequency, with a predetermined cutoff frequency; and a fourth operational section for outputting, based on the output signal having a lower resolution produced by the first operational section and the quantization noise components near the intended wave frequency extracted by the third operational section, a signal obtained by removing the quantization noise components near the intended wave frequency from the signal having a lower resolution amplitude-component-wise than that of the input signal, wherein the filter is a low-pass filter if a zero point of a noise transfer function of the first operational section is 1, and the filter is a bandpass filter if a zero point of the noise transfer function of the first operational section is a complex number whose magnitude is 1, and wherein the predetermined cutoff frequency of the third operational section is decided such that a fluctuation level of a complex envelope of the signal outputted by the fourth operational section is equal to or less than a predetermined value.