发明名称 |
Converter, offset adjustor, and portable communication terminal unit |
摘要 |
The number of current sources and switches necessary for a plurality of unit D/A converters using equal reference currents, are drastically reduced to reduce the parasitic capacitance coupled to current output lines, by converting a plurality of digital signals of a predetermined bit, which are divided from an input digital signal, into an analog current unit D/A converters and by converting the analog current in a manner to correspond to the weights of the corresponding input digital signals, thereby to synthesize the currents. The fixed reference digital signal is inputted to the D/A converter for cancelling offsets. The offsets of a plurality of analog output signals in positive and opposite phases obtained by branching the output of the D/A converter are individually detected. After this, the DC offset values of the individual analog outputs are used as offset adjusted negative feedback signals for a desired value. One of them is the digital signal to be fed back to the input portion of the D/A converter whereas the other is the analog signal to be fed to a path portion obtained by branching the output of the D/A converter.
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申请公布号 |
US5515047(A) |
申请公布日期 |
1996.05.07 |
申请号 |
US19930170411 |
申请日期 |
1993.12.20 |
申请人 |
HITACHI, LTD. |
发明人 |
YAMAKIDO, KAZUO;KOBAYASHI, YOICHIRO;OTSUKA, MASANORI;OKAZAKI, TAKAO;ISHIHARA, YUKIHITO;NISHIKAWA, NORIMITSU;TAMBA, YUKO |
分类号 |
H03M1/10;H03M1/68;H03M1/74;H04B1/40;(IPC1-7):H03M1/06 |
主分类号 |
H03M1/10 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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