| 摘要 |
PURPOSE: A receiving device of a mobile phone system is provided to reduce an offset of a higher active filter without using an analog-digital converter, thereby reducing an initialization time of a mobile phone system. CONSTITUTION: A higher active filter(100) outputs two differential signals(V1,V2). An increase and decrease unit(600) inputs one of the tow differential signals. An analog-digital converter(200) inputs an output of the increase and decrease unit(600), and inputs the other output of the filter(100), to convert into a digital signal. A digital signal processor(300) inputs the digital signal, and outputs a control signal. A switch(400) inputs the two differential signals to form a feedback loop, and inputs the control signal to output the signals(V1,V2). An offset detector(500) inputs the control signal to form the other feedback loop, and extracts an offset value(Vd) from an output of the switch(400) to transmit the value to the increase and decrease unit(600), then increases and decreases the differential signals.
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