Coded data generation or conversion – Analog to or from digital conversion – Digital to analog conversion
Patent
1993-12-20
1996-05-07
Hoff, Marc S.
Coded data generation or conversion
Analog to or from digital conversion
Digital to analog conversion
341153, H03M 106
Patent
active
055150470
ABSTRACT:
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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Ishihara Yukihito
Kobayashi Yoichiro
Nishikawa Norimitsu
Okazaki Takao
Otsuka Masanori
Hitachi , Ltd.
Hoff Marc S.
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