Title:
デジタルアナログ変換器
Document Type and Number:
Japanese Patent JP3978744
Kind Code:
B2
Abstract:
A D/A converter (8) includes a DELTA SIGMA modulator (9) applying Delta-Sigma modulation to a digital signal S1 in order to generate a code sequence S2, and first and second post-filters (10,11) as a first-order analog low-pass filter, respectively, which is connected in cascade to the subsequent stage of the modulator (9), in which low-pass filtering on the code sequence S2 is executed so as to output an analog signal Sout. The post-filter (10) is set to have a cutoff frequency fcb which falls in the frequency range from fca to fHa, where the fca is a cutoff frequecy of the post-filter (11) and the fHa is a maximum frequency thereof. Since the respective attenuation characteristics of post-filters (10 and 11) are synthesized, an overall attenuation characteristic Gab between the both filters is able to have the characteristics of a desired second-order filter. The synthesized attenuation characteristic Gab allows the D/A converter to simultaneously execute processing such as de-emphasis in the frequency range between the both cutoff frequency fca and fcb, and elimination of high-frequency noises over the frequency range of the cutoff frequency fcb. As a result, the D/A converter with a small circuit scale can be provided.
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Inventors:
Toru Ohashi
Yuji Yamamoto
Yuji Yamamoto
Application Number:
JP2002216959A
Publication Date:
September 19, 2007
Filing Date:
July 25, 2002
Export Citation:
Assignee:
Pioneer Corporation
International Classes:
H03M3/00; H03M1/66; H03M3/02
Domestic Patent References:
| JP7297680A | ||||
| JP2000113655A | ||||
| JP2001223589A | ||||
| JP2000183749A | ||||
| JP11150477A | ||||
| JP63254825A | ||||
| JP4302222A | ||||
| JP6232755A |
Attorney, Agent or Firm:
Nobujun Kobashi
Ritsumasa Kobashi
Ritsumasa Kobashi